This is the original, 2007 version of this piece.
I've created a new version of my...
...but I've retained this original version of the page so
people can verify what I said, when,
using the Wayback Machine.
Pitching Mechanics (2007)
a Cardinals fan, Mark Prior terrified me.
Then he was done.
what Jeff Passan says about the Inverted W in his book The Arm,
the fact is the Inverted W ended Mark Prior's career as well as the
- Jeremy Bonderman
- Anthony Reyes
September 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.
Mark Prior - Frame 23
In Frame 23, Mark Prior is just about to break his hands.
Mark Prior - Frame 24
In Frame 24, Mark Prior has just
broken his hands and is starting his arm swing.
Mark Prior - Frame 25
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.
Mark Prior - Frame 26
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.
Mark Prior - Frame 27
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.
Mark Prior - Frame 28
In Frame 28, Mark Prior is at a
position that I call the
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
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.
Mark Prior - Frame 29
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.
Mark Prior - Frame 30
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.
Mark Prior - Frame 31
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.
Mark Prior - Frame 32
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.