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Updated October 29, 2020

Mark Prior Pitching MechanicsWhat happened to Mark Prior?

Mark Prior was an early adopter of a particularly dangerous form of Scap Loading, called the Inverted W, that created an especially bad form of Timing problem called Flat Arm Syndrome. That was worsened by the fact that Mark Prior did this in combination with another flaw called Hyperabduction.

Comparison of Nolan Ryan and Mark Prior

Mark Prior's Inverted W

Combine that with other problematic things Mark Prior was taught by Tom House, such as his upright, unathletic posture, and you had a pitcher who moved extremely inefficiently; who had to generate velocity with his arm because he wasn't able to do so with his body.

Comparison of Nolan Ryan and Mark Prior

Nolan Ryan vs. Mark Prior

This is an overview of what happened to Mark Prior. For more detail, see my...

What Happened to
Mark Prior

The question of what happened to Mark Prior is one that — stupidly, cruelly, and unnecessarily — is still in some doubt.

Largely due to Tom House and his enablers.

What Happened

I've used the sequence below to discuss Mark Prior's pitching mechanics.

The limit is that, while it shows WHAT Mark Prior did, it doesn't show the most important thing.

The impact on Mark Prior's Timing.

Mark Prior Pitching Mechanics

Mark Prior - Frame 28

As I said in 2007...

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 pitching 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 pitching arm is so late, he will dramatically increase the stress on both his elbow and shoulder.
Mark Prior Pitching Mechanics

Mark Prior - Frame 29

Why it's Bad

In the frames below, notice how high Mark Prior's Pitching Arm Side elbow gets.

Mark Prior Pitching Mechanics

Mark Prior - Frame 27

That's a problem because it keeps Mark Prior's pitching arm from getting UP on time.

Mark Prior Pitching Mechanics

Mark Prior - Frame 28

Instead of being UP when his shoulders start to turn, Mark Prior's pitching arm instead is FLAT.

Mark Prior Pitching Mechanics

Mark Prior - Frame 29

That's bad because it will increase the distance over which, and thus the force with which, Mark Prior's pitching arm will externally rotate, overloading the muscles of his shoulder.

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