While Mark Prior is the poster child for the Inverted W, it's important to understand that the Inverted W wasn't the root cause of the shoulder problems that ended Mark Prior's career.

Rather, a Timing problem was the root cause of Mark Prior's shoulder problems.

Mark Prior 2010

I say that because, as he tried to come back, Mark Prior eliminated his Inverted W but still couldn't stay healthy.

Why not?

Because Mark Prior's Inverted W was just a symptom of an underlying, flawed movement problem that, even when his Inverted W was eliminated, still created a problem that I refer to as Flat Arm Syndrome.

Arm Action, Arm Path, and the Perfect Pitch page 48

This piece explains how a number of things I believe Mark Prior was taught, in addition to breaking his hands with his thumbs down, forced him to develop his Inverted W arm action, his Timing problem, his Flat Arm Syndrome, and ultimately led to his shoulder problems.

Previous Writings About Mark Prior

I have written extensively about the Mark Prior, the Inverted W, and the root cause of his injury problems...

Just to be absolutely clear about my view of what caused, and what only contributed to, Mark Prior's injury problems, I have put this capstone piece together.

Mark Prior's Pitching Mechanics

This clip is one of the most important ones in my library because it shows a number of critical things about Mark Prior's stride that I believe are relevant.

Mark Prior's Stride

This clip shows Mark Prior's linear stride toward home plate, his rigidly upright posture and vertical spine, and his Inverted W arm action.

I would argue that these three things are inter-related, and I say that based on seeing the same three things in the mechanics of other pitchers.

In my opinion, Mark Prior's Inverted W is the result of the linear stride and the rigidly upright posture.

Comparing Nolan Ryan and Mark Prior

The clips below compare the arm actions of Nolan Ryan and Mark Prior, starting when Nolan Ryan's pitching arm is at roughly 0 degrees of external rotation (perpendicular) to his spine.

Nolan Ryan and Mark Prior Frames 15-17

One thing that is obvious is that Mark Prior's pitching arm is internally rotated at the moment that Nolan Ryan's pitching arm is flat and at 0 degrees of external rotation.

Nolan Ryan and Mark Prior Frames 15-18

As a result, Nolan Ryan's pitching arm is well ahead of Mark Prior's from the perspective of sequence.

Nolan Ryan and Mark Prior Frames 15-19

Nolan Ryan's arm is UP while Mark Prior's arm is still FLAT.

Nolan Ryan and Mark Prior Frames 15-21

Postural Differences

Why do Nolan Ryan and Mark Prior exhibit such a significant difference in their arm action and timing?

In my opinion, it's because they move differently.

These postural differences are obvious in the clip below. 

Nolan Ryan and Mark Prior

The comparison above is extremely important because it shows that, while Nolan Ryan and Mark Prior got to the same place, they got there very differently and, more importantly, at different rates.

Nolan Ryan and Mark Prior Frames 01-14

Nolan Ryan and Mark Prior's torsos are relatively similar as they start to stride toward the plate.

Nolan Ryan and Mark Prior Frames 14-22

However, they diverge as they go into foot plant, with Mark Prior's torso staying rigid and upright in comparison to Nolan Ryan.

Nolan Ryan and Mark Prior Frames 14-19

In my opinion, Mark Prior's less fluid and athletic movement pattern forced him to compensate by compromising his timing.

That overloaded his arm and worked.

For a while.

Why didn't Tom House teach Mark Prior to throw like Nolan Ryan?

Nolan Ryan and Mark Prior Frames 14-16

In the clip above, notice that, while Nolan Ryan's pitching arm externally rotates and his pitching arm side hand gets above his pitching arm side elbow, the same isn't true for Mark Prior.

Nolan Ryan and Mark Prior Frames 14-17

The clip above shows that the same pattern holds further on in Nolan Ryan and Mark Prior's delivery; where Nolan Ryan's pitching arm is smoothly rotating up and into position, the same isn't true for Mark Prior.

Nolan Ryan and Mark Prior Frames 14-22

In the clip above, notice how, while Nolan Ryan's arm smoothly and gradually gets up, the same isn't true of Mark Prior. Instead, his arm takes much longer to get up; it slowly works its way up, and then pops up at the last second.

Nolan Ryan and Mark Prior Frames 16-18

In fact, Nolan Ryan's arm is up as Mark Prior's arm is just starting to get up.

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