Mark Prior's Pitching Mechanics
September 27, 2007
I have long believed the root cause of Mark Prior's injury
problems was his pitching mechanics. I analyze Mark Prior's
pitching mechanics in a number of pieces.
In this piece, I analyze Mark Prior's pitching mechanics
using a very telling clip of him pitching at USC.
Mark Prior's 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 supposedly perfect pitching mechanics, let me
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'm fine with what I see. Mark Prior's arm
action is 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 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.
NOTE: If you doubt whether I said this and/or
when, you can verify it using
The Wayback Machine.
In Frame 29, Mark Prior is
landing on his Glove Side (aka GS) heel, but that's the
least of his problems.
Because his GS heel is down, we know
that Mark Prior's shoulders are starting to rotate.
However, his PAS arm isn't ready.
Notice how his PAS forearm is not yet
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
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.
Flat Arm Syndrome
For a more detailed look at the root cause of Mark Prior's
shoulder problems, and the problems of pitchers like
Jose Fernandez, see my piece on
Flat Arm Syndrome.
FOR FURTHER READING
If you are interested in the topic of
Mark Prior's pitching mechanics, I have put together a number of
other pieces that discuss
Doubt What I Said When?
If you ever doubt when I said what, you can check using The
Wayback Machine at Archive.org. Here is
their capture of this page on January 13, 2008.
About The Author
Chris O'Leary never played baseball beyond grade school due
to a shoulder injury suffered due to poor pitching mechanics. As
a result, he is focused on ensuring that what happened to him
doesn't happen to anybody else.
The Epidemic is one way he hopes to achieve that goal.