This piece is my original analysis of...

• Mark Prior's Pitching Mechanics

While it's been superceded by better analyses, I've retained it so people can see what I said about Mark Prior, when.

Mark Prior's Pitching Mechanics

9/27/2007

I have long believed that the root cause of Mark Prior's injury problems is his pitching mechanics. While I have analyzed Mark Prior's pitching mechanics before, I haven't been able to do so using high-quality video or from the best angles. As a result, that has limited the quality of my analysis and the ability of my readers to see exactly what I'm talking about.
     However, yesterday a client sent me a clip of him pitching against Mark Prior. I have extracted a few key frames from that very high quality video that makes it very clear what Mark Prior's problems are.
     Before anyone gets on me about Mark Prior's having supposedly perfect pitching mechanics, let me explain something. The person who said that Mark Prior had perfect pitching mechanics is a guy named Tom House. Tom House also happened to be Mark Prior's pitching coach and designed Mark Prior's pitching mechanics. As a result, Tom House shouldn't be considered an impartial, objective observer and his pronouncements about Mark Prior need to be taken with a huge grain of salt.

In Frame 23, Mark Prior is just about to break his hands.

In Frame 24, Mark Prior has just broken his hands and is starting his arm swing.

In Frame 25, Mark Prior is continuing his arm swing and is striding toward the plate. Up to this point, I love what I see. Mark Prior's lower body and arm action are pretty much perfect up to this point.

Frame 26 is where Mark Prior starts to go off the rails. It's not obvious, but what Mark Prior is doing is leading his arm swing with his Pitching Arm Side (aka PAS) elbow. Some people call this breaking the hands with the elbows. The result is that Mark Prior's PAS elbow will end up much higher than is safe. That will put him in a position to damage both his elbow and his shoulder.
     I should point out that what Mark Prior does during his arm swing is very different than what Greg Maddux or Roger Clemens do during their arm swings, and that difference explains their very different fates.
     This difference is incredibly obvious, so much so that I can't believe the Cubs haven't picked up on it. For a couple of years, Maddux and Prior were both on their pitching staff, and you would think that someone would have thought to compare the similarities and differences between them as I have.
     But they haven't.

In Frame 27 you can see how Mark Prior has continued his arm swing, and you can see how his PAS elbow has continued to come up. The PAS elbows of Greg Maddux, Roger Clemens, Randy Johnson, and many other great pitchers never get this high during their arm swing. 

In Frame 28, Mark Prior is at a position that I call the Inverted W (or simply the "M"). Notice how his PAS elbow is both above and behind his shoulders and his PAS forearm is hanging down nearly vertically beneath it.
     This position isn't damaging in and of itself.
     However, by coming to this position, Mark Prior is ensuring that his PAS arm will not be in the proper position at the moment his shoulders start to turn. As with pitchers with other timing problems like rushing, because his arm is so "late" he will dramatically increase the strain on both his elbow and shoulder.

In Frame 29, Mark Prior is landing sharply on his Glove Side (aka GS) heel, but that's the least of his problems.
     Because his GS heel is planting, we know that Mark Prior's shoulders are just about to start rotating. However, his PAS arm isn't ready.
     Instead, it's extremely late.
     Notice how his PAS forearm is not yet horizontal. In a pitcher like Greg Maddux, his PAS forearm is much closer to vertical (e.g. pointed upwards and near the high cocked position) at this moment. Mark Prior's PAS elbow is also extremely, and unusually, high at this moment.

In Frame 30, Mark Prior's shoulders have just started to turn. Notice that the word "Trojans" on his chest has shifted to the right as his hips have started pulling his shoulders around. However, at this moment Mark Prior's PAS elbow is still extremely high. It is well above the level of his shoulders in a position of Hyperabduction. This can lead to an impingement injury of the muscles of the Rotator Cuff, as well as other problems.
     As an aside, one reason that I am so nervous about the long-term health of Anthony Reyes and Adam Wainwright of my Cardinals is that I see the same problem in their mechanics. As a result, I expect that they will experience similar problems as Mark Prior.

In Frame 31, Mark Prior's shoulders have continued to rotate and his PAS upper arm has externally rotated, which has caused his PAS forearm to "bounce" or lay back toward 2B. While this looks problematic, it is actually normal and doesn't not have much to do with Mark Prior's problems. This happens to every pitcher's PAS upper arm and forearm.

In Frame 32, Mark Prior has just released the ball. One thing you can see is that Mark Prior stiffens his GS knee near the release point. This is a trick that some pitchers employ that makes me nervous because I think it can increase the stress on the elbow (and possibly the shoulder as well). There are better, and less stressful, ways of maximizing the rate and distance the hips rotate.