Author Mark Hyman of The New York Times recently published an article about two studies that have shown curveballs are no more stressful on the arm than fastballs. Hyman uses this information to openly question the wisdom that says curveballs are bad for young arms. [Click here to read Hyman's article in full.]

The chief problem with Hyman's article is that he seems to misinterpret the study's conclusion. The study found no link between curveballs and injuries, but Hyman appears to have interpreted this to mean that curveballs conclusively do not lead to injury. This is a logical fallacy.

It's unclear whether Hyman has an opinion of his own, but he did seek the opinions of Dr. Glenn Fleisig and Dr. James Andrews. He offers these opposing quotes from Dr. Fleisig and Dr. Andrews about the studies.

I don't think throwing curveballs at any age is the factor that is going to lead to an injury.

Dr. Fleisig's quotes in the article clearly indicate that he doesn't believe throwing a curveball is any worse than throwing fastballs or change-ups. They may be taken out of context, but Hyman sure makes it seem like Dr. Fleisig is very confident with this position.

It may do more harm than good -- quote me on that.

Dr. Andrews, on the other hand, seems to have a deeper understanding of what the studies actually reveal. While the studies did not reveal an obvious link between curveballs and injuries, Dr. Andrews recognizes that a link may still exist outside the scope of these studies.

Obviously, a more stressful pitch is more risky than a less stressful pitch. That's just not all there is to it.

The two recent studies were inspired by a study published in 2006 by Dr. Fleisig, Dr. Andrews, et al. That study's clinical relevance was summed up in its abstract:

Because the resultant joint loads were similar between the fastball and curveball, this study did not indicate that either pitch was more stressful or potentially dangerous for a collegiate pitcher. The low kinetics in the change-up implies that it is the safest.

Essentially, this means that the slower your arm moves, the safer the pitch. This principle carried over into the follow-up studies on youth pitchers, and it's the main flaw with all three.

The studies measure raw joint torques but they don't account for basic mechanical or functional differences between the pitches which already vary from pitcher to pitcher anyway.

The key factor that is essentially unaccounted for in these studies is forearm action - pronation versus supination. A properly pronated pitch is not equivalent to a supinated pitch no matter how similar the kinetic measurements may be.

The muscles of the flexor-pronator mass can provide support against the valgus force that damages the ulnar collateral ligament (UCL). When a pitch is thrown with the forearm in a supinated position throughout the delivery - as most pitchers throw their curveballs - these muscles do not provide the same support for the UCL. This makes UCL tears more likely even if there is no difference in the measured stress levels between pitches.

Additionally, powerful pronation through release helps decelerate elbow extension and helps prevent the olecranon process from slamming into the olecranon fossa on the back of the elbow. When the elbow slams closed it can lead to inflammation of the hyaline cartilage and excessive bone growth including lengthening of the ulna, bone spurs, and bone chips.

When a supinated curveball is thrown, a pitcher risks injury in a number of ways. Without paying attention to what the pitcher is actually doing with his body, these studies simply do not reveal much. They certainly don't give carte blanche to start flipping curveballs like they're going out of style.

Yesterday, for the second time in his 3-season stint with the Texas Rangers, Brandon McCarthy was diagnosed with a stress fracture of the scapula. With consideration to the number of muscles that move and stress the scapula when throwing a baseball, it's amazing how rarely scapular stress fractures are diagnosed in pitchers.

In 1987, Texas Rangers pitcher Edwin Correa was diagnosed with a stress fracture in his scapula. Correa never again pitched in the Major Leagues.

In 2003, Kurt Ainsworth, then pitching for the San Francisco Giants, was also diagnosed with a stress fracture in his scapula. Ainsworth recovered but pitched in only 7 more games in the Majors, all in 2004.

The most detailed information that I can find on this type of injury is what I know from McCarthy's previous stress fracture and what I learned from reading "Scapular Stress Fracture in a Professional Baseball Player," a study published in the American Journal of Sports Medicine in February 2007.

The study takes a look at the injuries suffered by an unidentified right-handed Major League Baseball starting pitcher. This pitcher's mechanics were apparently a mess. Prior to his scapular stress fracture, the pitcher had been through Tommy John (ulnar collateral ligament replacement) surgery and a "transient episode of subacromial bursitis" in his shoulder. In the three years that followed his recovery from the stress fracture, this pitcher had surgery on both his elbow and shoulder, though neither was directly related to his scapula injury.

Pitcher X's stress fracture was located on the lower outside edge of the scapula bone, called the lateral border. The doctors who authored the study concluded based on the fracture's location that the likely cause of Pitcher X's stress fracture was "repetitive stress in the area of the teres minor attachment."

Repeated stress on muscles and bones causes them to grow stronger and more resilient over time. When the growth can't keep up with the stress, stress fractures occur in bones and tendonitis occurs in muscles. In the case of Pitcher X, his teres minor grew stronger at a faster rate than his scapula. Eventually, the stress fracture developed.

The teres minor attaches the lateral border of the scapula to the outside edge of the back of the humerus (see the diagram). It is one of the muscles of the rotator cuff, and its primary function is external rotation. The teres minor is stretched by internal rotation when the back of the humerus turns away from the scapula. It is also stretched as the humerus moves away from the scapula.

In the delivery, the rotator cuff contracts most powerfully during the follow-through as it tries to stop the arm from twisting and flying out of socket. The faster the humerus is moving away from the scapula and the greater the rate of internal rotation, the more powerful the contraction must be to maintain joint stability.

Brandon McCarthy's follow-through is a little unique in this regard. I missed it when I reviewed his mechanics last month because I wasn't looking for it. Of course, maybe I'm just seeing what I want to see. Here's the clip I used for my original analysis:

Notice that, after release, McCarthy's arm continues to move away from his scapula and towards his head. Even at 210 frames per second, it only lasts for a few frames, so look closely. You might even see his shoulder blade "hump up" a little around this time.

This high-intensity eccentric contraction stresses the teres minor muscle more than the other rotator cuff muscles because its scapular attachment is the furthest from the joint.

A reasonable outlook

Rangers general manager Jon Daniels has reportedly said that McCarthy will not pick up a baseball for several weeks. That might be a bit of an exaggeration, depending of course on the severity of the stress fracture. McCarthy himself said the pain has been there for a while and that he feels like he did in 2007.

McCarthy suffered and recovered from an injury similar to this one back in August/September 2007. I can not say how similar because I do not know the exact location and severity of either his 2007 or his 2009 stress fracture. McCarthy recovered from the 2007 injury fairly quickly and missed only a month of Major League action.

Rest is the only way to recover from a stress fracture. While the bone heals and gets stronger, the offending muscle atrophies and weakens - killing two birds with one stone. Often times, the pain will subside long before the bone fully heals, sometimes months after diagnosis. It might be that McCarthy's original stress fracture never healed.

I believe the Rangers are more or less "on the lookout" for injuries like this with McCarthy, so I feel that this injury is probably an early-stage stress fracture. They will probably keep him from throwing until scans no longer show signs of the fracture. Hopefully, this is no longer than 3 or 4 weeks.

Last month, I said that if McCarthy could stay healthy and have success with his mechanics, there was no reason to change them. I now believe there's sufficient reason to start that process. McCarthy and the Rangers need to give serious consideration to making major changes in his delivery.

[I suspect that Pitcher X is Darren Dreifort, though the article was written by doctors in Baltimore.]

Unlike Matthew Purke, Tyler Matzek is routinely regarded as a pitcher with an easy, repeatable delivery. Matzek is able to throw 90-94 mph with ease and has recently been as high as 98 mph according to several reports. He throws a curveball that has plus potential, but scouts from the Major League Scouting Bureau have a lesser opinion of its current quality than Baseball America does.

Dr. Mike Marshall weighed in on Matzek in his Questions/Answers 2009 file. If you are at all familiar with Dr. Marshall's view of the 'traditional' pitching motion, you'll recognize that his comments border on praise. Dr. Marshall had the following to say:

Mr. Matzek's version of the 'traditional' baseball pitching motion is not as injurious as many I have seen... I doubt that he will suffer a serious pitching injury. However, he will never be as good as he should have been.

As with Purke, I was intrigued by the generic mechanical comments I'd read in scouting reports. This time, though, the comments were about an easy, repeatable delivery. The comments from Dr. Marshall further piqued my interest. I dug around and found a video similar to the one I used for my Purke article.

Here's the video I looked at, courtesy again of Baseball Factory:

Even though it's a warm-up pitch, I chose to use the first pitch in the video as my example. The stills in the two images below were taken from this same pitch.

In the first frame, you can clearly see that Matzek takes the ball primarily toward second base during his pick-up. If you looked at my review of Purke's mechanics, you'll remember that he took the ball primarily toward third base. Skipping ahead to the fourth frame (approximately the release point), you can see that Matzek has much less side-to-side movement than Purke. His driveline to the plate is very direct compared to most 'traditional' pitchers, extremely efficient.

The second frame shows Matzek's body position at foot-plant, in the 'traditional' cocked position, where he seems to have a nearly straight-forward stride. At 90° of flexion, the ulnar collateral ligament is at its most vulnerable. At this stage Matzek's arm is fairly straight, so the late forearm turnover and reverse forearm bounce that follow are less of a problem. This is part of why Dr. Marshall views Matzek's arm action as less injurious.

As Matzek increases his elbow flexion, he also tilts his shoulders to the glove side and raises his elbow. This action helps limit his forearm flyout by effectively straightening his elbow's path. At his approximate release point, you can see that his forearm is nearly vertical.

In the video Dr. Marshall reviewed (of a side session), he mentioned that he was concerned about Matzek's forearm flyout. The video that I reviewed seems to show that Matzek's forearm flyout is minimal.

The first frame in this image is from shortly after release. Matzek's elbow is flexed and his wrist is pronated to the point where his palm is nearly facing up. This indicates two things: (1) Matzek pronates his release very powerfully, and (2) Matzek may be using his latissimus dorsi to internally rotate his arm instead of using his pectoralis major to horizontally flex his arm.

At this normal frame rate, it is practically impossible to tell for certain whether or not Matzek pronates into release, but he sure appears to be doing so.

Dr. Marshall says that because Matzek's stride is "too closed," he must be using his pectoralis major to horizontally flex his pitching arm. If he were actually horizontally flexing his arm to throw the baseball, I don't believe that Matzek could achieve the arm position shown in the first frame of this image.

By the second frame, his primary arm deceleration phase is done. The continuation of his body action in the next two frames causes his arm to wrap across his body. I believe the appearance of recoil is an illusion created when Matzek stands up to field his position.

So... what are you saying?

Matzek throws some high-quality pitches from a relatively safe, easy, and repeatable delivery. From an objective perspective, there are fewer risk factors than most 'traditional' pitchers. For a high school pitcher, he's a lot more polished than I would have expected.

I have reason to believe that he throws three different fastballs and a pronated curveball. After doing my research, I like him more than I did, and I'm kind of upset that there's no chance he'll be around when the Texas Rangers pick at #14. I guess I can hope, though.

You might also want to check out dirtberry's YouTube channel for more on Tyler Matzek.

Spring, TX - a suburb of Houston - has produced quite a number of early-round draft picks over the past several years. It looks like Klein's Matthew Purke will join a list that includes former Klein players Josh Barfield, Chris George, and David Murphy, as well as Josh Beckett, Sam Demel, and Daryl Jones from Spring High School.

Purke stands at 6-foot-3 and weighs 180 pounds. Scouts like his projectability and believe he could add velocity as he gets stronger. He already sits at 92-94 MPH, occasionally throwing a tick or two harder. His primary off-speed pitch is a slurve-type offering called a slider by Baseball America and a curve by the Major League Scouting Bureau. Whatever you call it, it's one of the best breaking balls in this year's high school draft class.

Conflicting reports from the same two sources have his change up somewhere between "unknown" and "good."

Purke is believed to have a strong commitment to Texas Christian University in Fort Worth, so signability has become a concern for some clubs. Rumors of his signing bonus demands have ranged from $2 million to $7 million, but the most recent rumors have him in the neighborhood of $3 million.

Almost every report on Purke has mentioned something about questionable mechanics. Typically, high school deliveries are full of flaws and quirks, but rarely do these scouting reports go out of their way to mention them.

Baseball America mentions Purke's slinging action, saying that it is neither violent nor smooth. I guess that would be... Average? Typical? Expected? Outside of this specific mentioning of a flaw, I could only find generic references to his mechanics. I wanted to have a look for myself.

I located a solid video on YouTube, looked at it, and made some still photos. Here's the video, courtesy of Baseball Factory: [video has been made private and can no longer be embedded]

There are two big things that jump out at me, but first, I want to say that outside of his arm action, there really isn't much to complain about. He steps nearly straight forward, landing only a few inches closed.

Purke stays closed very well and gets great hip rotation and shoulder rotation. He even stands relatively tall through his release. His core does its job very well.

If I had to pick one part of his body action to complain about, it would have to be his somewhat stiff front leg. That might be the source of the reported inability to repeat his delivery consistently.

The still shots below were taken from the same pitch, the first one in the video.

Now, here are the flaws in his arm action as I see them. In the first frame, you can see that Purke's entire pitching arm has been moved about as far toward third base as possible. Skipping ahead to the final frame, you get an idea of how much horizontal acceleration takes place. When his arm finally starts moving forward, the centripetal force from the curved path results in forearm flyout. The Baseball America "slinging" comment is dead-on.

Pronated releases can help protect against the negative effects of forearm flyout, but there aren't enough frames available to be able to determine if, or to what extent, Purke pronates into his release.

The second frame shows a massive scapular load at foot plant. This puts extra stress on the anterior capsule of the shoulder, and the extra movement of the head of the humerus places the glenoid labrum at risk.

Still in the second frame, his forearm is past horizontal, avoiding an inverted arm position, but his forearm is almost 180° of external rotation from the throwing position shown in frame three. This causes a late forearm turnover.

Because his elbow is flexed to near 90° during his late forearm turnover, he experiences a pretty intense reverse forearm bounce which puts his ulnar collateral ligament at risk.

Here's an overly simplistic look at his follow-through. The first frame shows where his arm winds up after primary deceleration. His arm continues in the curved path and winds up finishing hard toward third base. There is no recoil evident at this frame rate, and his arm winds up tucked in softly at his waist.

There could be some extra stuff going on in his shoulder, but the standard 30 frames per second video does not reveal it.

So... what are you saying?

Overall, Purke's mechanics could be a lot worse. That said, I'm not a fan of his arm action at all. The slinging action reported by Baseball America is clearly present, and he puts a lot of torque on his elbow. Long term, he has almost no chance to stay healthy with these mechanics.

Any team that drafts Purke will have to ask themselves which risk they want to take: leave his mechanics alone and risk his arm falling apart - or - change his mechanics and risk his stuff dropping off.

Robbie Ross. LHP, 5' 11", 185 lbs, Born: June 24, 1989. The 2008 2nd round pick of the Texas Rangers was said to have 1st round talent. Some minor signability concerns allowed Ross to slip into the early 2nd round where the Rangers selected him and eventually signed him for a reported $1.575 million signing bonus. He has yet to make his professional debut, but Ross could be in line to join the Spokane rotation in less than a month.

In a post-draft interview with Ross, Jason Cole of Scout's LoneStarDugout.com wrote the following:

Ross enters pro ball with an advanced changeup to go along with his fastball and slider. The southpaw’s fastball, as he explains in the interview, generally sits in the upper-80s, low-90s, but he has shown the ability to dial it up to 94 mph at times.

Out of the wind-up, Ross has a very high leg kick, reminiscent of Nolan Ryan's leg kick. After the kick, he starts to drift forward before sitting down on his back leg. This loads the leg very well, but it also lowers his potential release point. From lower release points, pitches take more flattened paths to the plate compared to pitches thrown from higher release points.

Ross keeps his front leg and hip closed until right before foot plant. When he lands, his center of mass almost completely stops moving forward. The momentum from his drive helps him open his hips really well and pulls his back foot forward off the rubber. I prefer this action to the foot drag seen in a lot of pitchers. (In Ross's 2008 MLB Draft Report, he is seen dragging his back leg like dead weight on his first pitch and last pitch, both presumably change ups. I did not identify any change ups within my video sample.)

Worth mentioning is the path his front foot takes toward his landing. His front leg moves in a sweeping motion. By the time his front foot plants, it is moving more toward third base than it is toward the plate. This gives him a soft landing and sort of kick-starts his hip turn as he turns his front leg to face the plate. I like the soft landing but prefer a more direct stride.

As one would expect, Ross's hip rotation leads to strong shoulder rotation. Ross maintains extremely level shoulders throughout. Because he keeps his shoulders level, his elbow moves in a sharp arc around his body. Ross picks up the ball mostly with his shoulder, but he reverse-rotates his shoulders and takes his elbow well behind his back and toward third base. All of this creates a curved path to release, resulting in the centripetal force that causes forearm flyout.

Ross's pronation seems to occur during release. This provides a degree of protection from the negative effects of forearm flyout, but at this frame rate and camera angle, it is impossible to determine whether it prevents his ulna from slamming into his humerus. I was unable to identify any sliders in my sample, so I do not know if he supinates his release for that pitch.

At foot plant, Ross's arm is nearly vertical, but active external rotation is still taking place. This creates a reverse forearm bounce where the baseball is moving toward third base and his elbow is moving toward first base. This indicates a large valgus torque in his elbow and is a risk factor for his ulnar collateral ligament.

Ross's follow-through is where things get interesting. The continuation of the centripetal force described above causes his arm to wrap slightly across his body. There is some recoil, so I have some concern for the posterior capsule of his shoulder, mainly the infraspinatus and teres minor muscle tendons.

Finally, Ross has a weird little hop-twist after everything slows down. This is probably caused by a continuation of his powerful shoulder rotation. He ends in an athletic yet awkward looking stance.

Joseph Ortiz. LHP, 5' 7", 175 lbs, Born: August 13, 1990. When Ortiz debuted with the Low A Clinton Lumberkings last season, he was only 17 years old. Definitely one of the smaller players in the league, Ortiz pitches beyond his stature. Even as one of the youngest players in the league, Ortiz's only statistical fault was a high walk rate - 4.5 per 9 innings. He struck out just over 7 batters per 9 innings and allowed just under 6.5 hits per 9 innings.

This winter, Cole compared Ortiz to former Rule V pick Fabio Castro because of their similar body types and repertoires. From Cole's scouting report:

The lefty constantly attacked hitters with his 87-91 mph fastball... hard, late-breaking slider... [and] a promising, occasionally used changeup...

Ortiz has a very compact delivery without a lot of flair or wasted movement. His stride is fairly standard, and he lands noticeably closed. His front leg sweeps like Ross, but Ortiz puts his foot down before it sweeps all the way across.

Ortiz pulls his elbow down and to the side as he flexes his trunk forward. This can help raise the release point but prevents a few trunk muscles from adding to the pitch and puts a little extra stress on his spine.

His hip rotation isn't great, and he drags his toe in the dirt pretty firmly. Ortiz flexes his trunk over his front hip, so hip rotation - or lack thereof - isn't a huge factor for him. This drives his throwing shoulder in a nearly straight line toward home plate.

Ortiz takes the ball only slightly behind his back, but noticeably drives his elbow toward first base before as he explodes toward release. This lateral movement causes forearm flyout, but Ortiz, unlike Ross, pronates late, making him more susceptible to its negative effects.

Despite his compact delivery, Ortiz has a late forearm turnover. This leads to active external rotation at his shoulder after foot-plant and creates a reverse forearm bounce where, like Ross, the ball and his elbow are moving in opposite directions.

Ortiz's arm also wraps slightly across his body, but with a more alarming recoil. Ortiz's arm appears to collide with his rib cage after the throw. The collision doesn't appear to be terribly violent, but the leverage caused by the impact can place extra stress on the posterior capsule of the shoulder where the muscles are already contracting to help decelerate the arm.

At the very end, Ortiz actually does have a little flair. Instead of a hop-twist, Ortiz's post follow-through action resembles the finish of Dr. Mike Marshall's pitchers. His shoulders and arm point at the target while his lower half turns toward second base.

This doesn't mean much for his pitches or for his health, but it's notable because it puts him in a horrible fielding position. I imagine that you'd see a lot of bunts against him in close games.