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.]

In limited action in 2008, Nelson Cruz finally started hitting Major League pitching to the tune of .330/.421/.609. Given the small sample size, people openly questioned whether he had actually turned the corner.

Through Friday, April 17, 2009, Cruz was off to a .282/.356/.718 start, more or less a continuation of his 2008 success. Using PITCHf/x data through the first 10 games of 2009 and some stats from Nelson Cruz's FanGraphs profile, here's a little plate discipline analysis to see if it supports his impressive start.

The black boxes in these charts are approximations of the actual strike zone. Based on average PITCHf/x data for Cruz's at-bats, the bottom of Cruz's strike zone is about 1.6 feet from the ground, and the top of his strike zone is about 3.4 feet from the ground. The left and right edges of the zone are approximated at 1 foot to either side of the plate based on half the plate's width (8.5 inches) plus some wiggle room for pitches that scrape the black (3.5 inches). (NOTE: All location graphs are from the catcher's perspective.)

The first chart shows us what Cruz has been swinging at by location and by pitch type.

Based on this chart, Cruz has mostly been swinging at strikes. According to his O-Swing% at FanGraphs, only 20.2% of these pitches are outside of the strike zone. That is the lowest of his career. Since his 2006 Rangers debut, his O-Swing% has dropped every season - 29.4% in 2006, 26.5% in 2007, and 23.1% in 2008.

Notice that Cruz hasn't swung at many pitches near the bottom or near the outside edge of the zone. This has helped Cruz lay off of breaking pitches away. Through 10 games, Cruz had not swung at a single pitch off the outside edge of the plate.

The second chart shows us what Cruz hasn't been swinging at by location and by pitch type.

This chart fills in the obvious holes from his swings chart. There are a lot of pitches in the zone low and away that Cruz has not swung at. According to his Z-Swing%, Cruz has swung at 78.5% of pitches in the zone. Based on that stat, the chart doesn't exactly match up. It appears that he's been taking pitches in the zone more often than 21.5% of the time. This could be the result of the PITCHf/x strike zone not matching up with the zone being called by the umpires.

Without getting in too terribly deep, here's a quick look at the righty-lefty split broken down by location and pitch result. The small sample against lefties in the first 10 games doesn't give us much to look at, but the righties scatter plot is interesting.

The PITCHf/x strike zones for Cruz appears to be pretty accurate. Keep in mind that some of the strikes outside of the zone were swung at.

Let's look at Cruz's Z-Swing% again. My rough count based on my unofficial strike zone suggests a 61:23 ratio or a 72.6% Z-Swing%, which would still be a career high for him. From 2006 through 2008, Cruz's Z-Swing was very steadily between 70% and 71%.

This year, he's swinging at strikes more often, but he's also swinging at fewer pitches overall - 46.8% in 2009 versus 50.8% in 2006, 49.6% in 2007, and 47.1% in 2008.

April 19, 2009 Update: Cruz has reached base safely in all 12 games this season on 13 hits and 7 walks against only 10 strike outs. He is now hitting .289/.377/.667.

The numbers and charts say he's being more selective than ever. This can only be good news for Cruz, the Texas Rangers, and their fans. I believe that Nelson Cruz has finally arrived.

Some other observations:

• Very few pitches have been thrown low and in to Cruz. I wonder if his AAA scouting report says to stay away from that quadrant.

• Righties stand a good chance of getting Cruz to put the ball in play by throwing him up and in.

• Cruz's first-pitch strike percentages by year: 62.3% in 2006, 63.4% in 2007, 52.6% in 2008, 51.0% in 2009. It's a small sample size and might not mean anything anyway, but it is interesting.

• One step further, Cruz is seeing fewer strikes than ever: 52.5% in 2006, 52.4% in 2007, 50.2% in 2008, and 45.7% in 2009. Combined with the stat above, I'm pretty sure this means something.

• One concern: what happens when opposing pitchers start hammering that outside corner?

News broke late this winter that Texas Rangers RHP Brandon McCarthy would be experimenting with a slurve, a pitch half-way between a slider and a curveball. It was later confirmed that this pitch was intended to replace McCarthy's curveball. I had always believed his curveball was a plus, so this news left me confused.

Yesterday afternoon, Brandon McCarthy debuted his new slurve against Cleveland and PITCHf/x was ready to go. On television, the new pitch didn't look that new, seemingly just a little harder with a little bit sharper break, and more than one person wondered if McCarthy was throwing both a slider and a curve ball.

I grabbed the PITCHf/x data from yesterday's game (April 9, 2009), and decided to compare it with a similar outing. I settled on McCarthy's April 9, 2007 start at home against Tampa Bay. In each start, PITCHf/x identified 4 different pitch types: fastball, curveball, slider, and change up. PITCHf/x data is never perfect, but there's still a lot of great information.

Let's first compare his release points from the catcher's perspective.

At first glance, it appears that McCarthy's release point has moved about 6 to 10 inches toward third base in the past two years. While definitely interesting, this may or may not actually be the case. In 2007, release points were measured at 55 feet from the back corner of home plate, but the 2009 release points were measured at 50 feet from the back corner of home plate.

Taking a bit of a deeper look reveals that McCarthy's release of his change up is very consistent with that of his fastball with a few stragglers straying up a couple of inches. In 2007, McCarthy's curveball release was a little higher and a little closer to first base, but in 2009, his curveball/slider release is noticeably higher but directly above his fastball release.

Take a look at the pitch movement scatter plots below. Vertical movement is calculated compared to gravity - an approximation of the Magnus effect. This means that zero vertical movement is equal to gravity's effect, while a negative number drops more than gravity and a positive number drops less than gravity.

Based on the PITCHf/x data shown in the graph, McCarthy's slurve is measurably different from his 2007 curveball. To further illustrate the difference, I grabbed velocity data for the two pitches as well. His average curveball velocity in the 2007 game was 73.47 mph, and his average slurve velocity in the 2009 game was 79.81 mph.

The most important difference between the old curveball and the new slurve is pretty simple: control. In the 2007 game, McCarthy threw 40% (10/25) of his curveballs for strikes. In the 2009 game, McCarthy threw 75% (15/20) of his slurves for strikes.

Yesterday, McCarthy threw 10 of 13 change ups for strikes. He had outstanding overall command of his off-speed stuff, but he really struggled with his fastball command, throwing only 34 of 60 (56.7%) for strikes.

I've noted this in the past, and it's still a major issue. McCarthy has a tendency to drag his arm behind his body when he throws his fastball. This is usually caused when the front shoulder "flies open" by turning toward home plate before the arm is ready to throw. The pitching arm tries to play catch up, but pitches usually wind up high and a tick or two slower when this happens.

In the 3rd inning, pitching coach Mike Maddux trotted out to chat with McCarthy. When he left, McCarthy's fastball jumped from 86-90 to 89-92 for his last 2.1 innings, and he was throwing it down in the zone. PITCHf/x is missing 5 pitches in this span, but after the visit, McCarthy rattled off 10 strikes on his next 12 fastballs.

Outside of that stretch, McCarthy threw only 50% strikes with his fastball. On the up side, Maddux appears to be on top of this, and I expect improvement in this aspect of McCarthy's game throughout the season.

Here are some quick shots:

• In the 2007 game, McCarthy's fastball was 10" to 15" above gravity, and his curveball was 8" to 13" inches below gravity. That's a visual 18" to 28" of vertical separation between the two pitches. I don't have a comparison ready, but that's a huge difference.

• McCarthy's fastball is straighter than ever. He's getting better back-spin, so the ball might appear to rise more, but his fastballs are all clustered around zero horizontal movement. In the 2007 game, he was getting a lot more arm-side movement.

• McCarthy is a tall guy, but it's pretty crazy that he lets go of the baseball when it's nearly 7 1/2 feet off the ground. A fastball to the bottom of the strike zone travels vertically down nearly 6 feet!

• Joey Matschulat at Baseball Time in Arlington took a look at McCarthy's PITCHf/x data as well - Profiling Brandon McCarthy: A Pitch F/X Snapshot.

This is Part II of a series that examines the Texas Rangers 2009 revenue outlook in a rough version of the framework laid out by Vince Gennaro in his fantastic book Diamond Dollars. Check out the Offline Reading list for other great reads.

In Part I, Texas Rangers Win-Curve Part I: Wins vs. Attendance, I walked through a model for predicting 2009 home attendance based on the team's on-field success as measured by wins.

Part II aims to add another piece to the puzzle by determining a team's chances of making the playoffs for a given number of wins.

WHAT EVERYONE KNOWS

Two types of teams make to the playoffs: 3 division champions and 1 wild card team.

The more games a team wins, the better its chances are for making it into the playoffs by either method.

In reality, for a given number of wins, a team will either make it to the playoffs or not. There are only two outcomes: 'yes' and 'no'.

MODELING THE DATA

Because there are only two outcomes, the data can be modeled with a logistics curve. The curve is created by a generalized binomial regression. Basically, using an independent variable (wins), it determines the probability that the dependent variable (team makes the post-season) is true.

I gathered 11 years of historical data for the American League in its current alignment - since Tampa Bay's inaugural season in 1998.

I ran regressions for each division and for the American League as a whole.

THE RESULTS

One hypothesis that I was eager to test was that for teams in smaller divisions, like the 4-team AL West, the odds of winning the division (and therefore the odds of making the playoffs) are greater than for teams in a 6-team division like the NL Central.

I tested this hypothesis by comparing the curves for each of the three divisions against the American League curve. Essentially, all 4 curves are the same but shifted either to the left or to the right.

The AL West curve, surprisingly, is shifted right, meaning it is harder to make the playoffs in the AL West than in the AL as a whole. The AL Central curve is shifted left, and the AL East curve showed a right shift approximately equal to the shift in the AL West curve.

At 92 wins, an AL team has had a 66.96% chance to make the playoffs. The AL West, AL Central, and AL East have had 62.69%, 78.24%, and 61.94% chances, respectively, at the 92-win level.

Since it has been easier to make the playoffs in the 5-team AL Central than it has been in the 4-team AL West, the hypothesis does not hold up. The difference between the AL West and AL East was barely noticeable.

TEXAS RANGERS POST-SEASON PROBABILITY

The two curves that apply to the Rangers, the AL curve and the AL West curve, are fairly similar. At 80 wins, the AL curve shows a 0.35% chance, and the AL West curve shows a 0.24% chance.

In what appears like it could be a weak division in 2009, 85 wins might be enough to get the Rangers in. Historically, though, 85 wins has resulted in only a 4.70% chance on the AL curve and an even smaller 3.58% chance on the AL West curve.

If the Rangers make the improbable jump from 79 wins to 95 wins, the AL curve gives them a 90.88% chance of making the post-season, while the AL West curve gives them an 89.59% chance.

Based on the 2009 outlook, if any AL West team can get to 95 wins, it should win the division handily. One team reaching that level would have a fair amount of shock value by itself, but if two teams hit the 95-win mark, it would be absolutely stunning.

APPLYING THE POST-SEASON EFFECT

When a team makes the post-season, the fan response typically includes increases in season ticket sales, television ratings, and merchandise sales. This post-season effect has a tangible benefit on team revenue for current and future seasons.

According to Gennaro's model, a net present value (NPV) is calculated for the post-season effect. For each win, the NPV is multiplied by the post-season probability for that win total, and the resulting value is added to that point on the win-curve.

In Part III, the dual focus will be on turning attendance figures into attendance dollars and assigning a value to the post-season effect.

It has become somewhat fashionable to blame Mark Connor for Eric Hurley's shoulder problems - a torn rotator cuff and frayed labrum. Without a full blown analysis of Hurley's arm action, though, it is also hard to say with certainty that his mechanics were responsible.

Given the nature of these injuries, though, Hurley's mechanics and hamstring are far more likely than Connor's teachings to be the cause of Hurley's shoulder injuries.

ANATOMY

Like any soft tissue in the body, rotator cuff muscles and tendons are torn gradually over time as stress creates micro-tears that build up and compound. There are exceptions, of course, but most of them involve severe external trauma like violent collisions and power lifting.

In pitching, the rotator cuff contracts most powerfully during the deceleration phase as it tries to keep the humerus from twisting and flying out of socket.  When the arm moves across the body, the head of the humerus becomes an obstacle to this contraction.  This forces the muscles to contract "around a corner" which adds more tension to the muscle than it can create on its own.

A frayed labrum is an early stage SLAP (superior labrum from anterior to posterior) lesion. Later stage SLAP lesions are commonly referred to simply as "torn labrums". The lesions are caused by the compressive force and friction created when the long head of the biceps brachii contracts and pulls directly on the glenoid labrum in an unnatural manner.

Certain arm actions, most notably transverse hyperabduction of the shoulder (scap-loading), can position the head of the humerus as an obstacle to the contraction of the biceps creating extra tension on the labrum where the long head of the biceps attaches.

Since part of the long head of the biceps merges with the labrum, SLAP lesions can sometimes be misdiagnosed as biceps tendinitis.  This is was the reported initial diagnosis for Hurley's shoulder injury on July 30, just three days after his final start of 2008.  On August 1, the Rangers reported that it was, in fact, shoulder soreness.

ATTACK OF THE HAMSTRING

Hurley was cruising along fairly well before he injured the hamstring of his left leg - his landing leg.

The hamstring of the landing leg experiences an eccentric contraction as the upper body moves forward over the waist. A negative change in the muscle's flexibility can decrease the amount of trunk flexion and/or shoulder rotation that occurs during a pitch. Since the body is less engaged in the deceleration of the arm, the shoulder handles more of the load than it would with normal hamstring flexibility.

Limited trunk flexion or shoulder rotation can cause the throwing shoulder's forward movement to stop early, even though the arm tries to continue moving toward the plate. The force of this action slings the arm across the body and moves the head of the humerus into the path of the muscular contraction as described above.

Hamstrings are notoriously slow-healing muscles, and flexibility can be compromised for a long period even after the muscle is fully functional.

Hamstring injuries will not always lead to shoulder injuries, but they represent a huge risk factor for someone already dealing with a weakened shoulder.

WAS HURLEY'S SHOULDER ALREADY WEAKENED?

The answer to this question simply has to be, "Yes."

In 234 minor league innings over the last two seasons, Hurley worked primarily with Rick Adair, Terry Clark, and Andy Hawkins - one of whom has one of the greatest mustaches in baseball.  All three coaches are extremely well regarded; none of them is Mark Connor.

Mark Connor was Hurley's primary pitching coach for about 32 innings, all in 2009. (Hurley had a 7.1-inning rehab start in Frisco near the end of that 32-inning span.) 32 innings is simply not enough to tear the healthy rotator cuff of a professional pitcher - someone whose rotator cuff should be exceptionally strong and well conditioned.

Barring severe external trauma, his shoulder must have been compromised before reaching the Majors and long before he hurt his hamstring.

SUMMARY

Hurley likely began damaging his shoulder well before his injuries became apparent. One can argue about the inevitability of a major tear, but excluding an external traumatic event, Hurley's mechanics are the most likely cause of the injuries.

When his hamstring started giving him trouble, his body compensated for that injury, effectively placing more (too much) stress on a rotator cuff that was, in all likelihood, already damaged.

Rotator cuffs simply don't tear suddenly enough to blame Connor for the injury.

Why Hurley was allowed to start that last game (and remain in it for as long as he was) is a different matter entirely.