Draft Prospect: Matthew Purke, LHP, Klein HS

Trip Somers • June 2, 2009 • Scouting

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.

Matthew Purke's arm action at four key points in his delivery.
Matthew Purke's arm action at four key points in his delivery. Click to enlarge.

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.

Purke's follow-through.
Purke's follow-through. Click to enlarge.

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.