Mark Prior's Pitching Mechanics
A Comparative Analysis
Few major league baseball pitchers have been the subject of
more debate than Mark Prior. I know that
Carlos Gomez has
discussed Mark Prior's pitching mechanics on The Hardball Times
least one occasion. I would like to offer a different
perspective on Mark Prior's pitching mechanics and an alternate
explanation for his arm problems.
When You Assume...
One thing I do for a living is work as a troubleshooter of
complex computer systems. A lesson I have learned repeatedly
(and sometimes the hard way) over the years is that one thing
that will get in the way of your understanding what is actually
going on in a system is the assumptions you make.
When Mark Prior, his coaches, and others compare his current
mechanics to the mechanics he used in the past and look for
things that have changed over the years, they are implicitly
assuming that his mechanics were good in the past and that the
root cause of his problems is that his mechanics have changed
over time. That seems like a reasonable assumption to make,
given that when he first came up
Mark Prior was widely and
loudly trumpeted as having perfect pitching mechanics.
However, over the years various credible people (e.g.
Steve Stone) have questioned the actual quality of Mark Prior's
pitching mechanics in light of his injury history. As a result,
I recently decided to compare Mark Prior's pitching mechanics to
the pitching mechanics of a couple of successful and relatively
durable pitchers and look for differences between their pitching
mechanics. The comparison pitchers I chose were Greg Maddux and
I believe I have found some differences that may help to
explain Mark Prior's injury problems and that suggest that Mark
Prior's pitching mechanics were never as good as they were
touted to be.
Comparison: Mark Prior & Greg Maddux
First, let me compare Mark Prior's pitching mechanics to
those of Greg Maddux, one of the most successful, and durable,
pitchers of recent history. The clip of Greg Maddux that I have
chosen is one from when Maddux was 19 years old and was at roughly
the same point in his career as Mark Prior. If you compare the
two clips, you will see two general areas of difference: lower
body action and arm action.
Mark Prior vs. Greg Maddux
Mark Prior and Greg Maddux do have quite different lower body
actions. Mark Prior's lower body action is relatively more
linear; during his stride his Glove Side (GS) foot moves pretty
much directly toward the target. In contrast, Greg Maddux's
lower body action is more rotational; rather than striding
directly toward the target, Greg Maddux sweeps his leg out
toward Third Base before landing with it pointing at the target.
Some have suggested that this difference means that Mark Prior
isn't as efficient as Greg Maddux. While this may be true, I
don't think it's especially significant. For one thing, Mark Prior is much
bigger than Greg Maddux, so he can stand to be slightly less
efficient with his mechanics. Second, if you look at Frame 30/101, you will see
that Mark Prior and Greg Maddux achieve similar levels of
hip/shoulder separation, which is the primary source of a
Mark Prior vs. Greg Maddux
Mark Prior and Greg Maddux also have very different arm
actions, and because what we are talking about are Mark Prior's
arm problems, I think this is a much more significant
difference. As you watch the two clips, watch what their
Pitching Arm Side (PAS) elbows do. After he breaks his hands,
Mark Prior's PAS elbow quickly gets quite high; it goes above
and behind the level of his shoulders. In contrast, after he
breaks his hands Greg Maddux's PAS elbow gets low and then stays
low. This difference is extremely obvious in Frame 28/097 and
Frame 29/099. Also note that in Frame 30/101, when Mark Prior
and Greg Maddux are both in the high-cocked position, Mark
Prior's PAS elbow is well above the level of his shoulders while
Greg Maddux's PAS elbow is well below the level of his
I believe this difference is significant because it is a
well-established fact that people like plumbers, pipefitters,
sheet metal workers, and others who constantly work with their
arms above their heads are much more vulnerable to shoulder
problems than is the general population.
Comparison: Mark Prior & Nolan Ryan
Some people will say it's not fair to compare Mark Prior
to Greg Maddux since Mark Prior is a power pitcher and Greg
Maddux is a finesse pitcher. As a result, let me compare Mark
Prior's pitching mechanics to those of one of the ultimate power
pitchers: Nolan Ryan. Nolan Ryan threw even harder than Mark
Prior but was relatively much more durable.
Mark Prior vs. Nolan Ryan
If you compare the two clips, you will see that Mark Prior
and Nolan Ryan have lower body actions that are relatively
similar; while their leg lifts are different, they both have a
fairly linear move toward the plate with their GS feet. What is
different about the two clips is their arm action. Mark Prior
and Nolan Ryan both break their hands in similar places and in
similar ways. The difference is that after breaking his hands
Mark Prior breaks his elbows vertically while Nolan Ryan breaks
his elbows more horizontally back toward First Base. As a
result, by Frame 28/10 Mark Prior's PAS elbow is above and
behind the level of his shoulders while Nolan Ryan's PAS elbow
is behind his shoulders but significantly lower. More
importantly, by Frame 30/14 Nolan Ryan's PAS elbow has dropped
to below the level of his shoulders while Mark Prior's PAS elbow
has stayed above the level of his shoulders. As with Greg
Maddux, I think this is a significant difference.
Mark Prior In Detail
So that I am perfectly clear about the problems I see in Mark
Prior's pitching mechanics, let me pull out a few frames from
the clip above and discuss them in detail.
Mark Prior - Frame 26
Frame 26 is where Mark Prior starts to go off the rails. It's
not completely obvious, but what Mark Prior is doing is leading
his hand break and arm swing with his Pitching Arm Side (PAS) elbow.
call this breaking the hands with the elbows. The result is that
Mark Prior's PAS elbow will end up much higher than is normal
(or safe). That will put him in a position to damage both his
elbow and his shoulder.
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, Nolan Ryan, Roger Clemens,
Randy Johnson, and many other great (and durable) 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
Inverted W. 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. Instead, it will be
"late". As with pitchers like Kerry Wood, who have similar
timing problems (e.g. rushing), this dramatically increases the
load on both the elbow and the shoulder.
Mark Prior - Frame 29
In Frame 29, Mark Prior is landing sharply on his 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. The problem is that Mark Prior's 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. I
believe that this places an extraordinary level of stress on
both the Rotator Cuff and the Labrum.
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
Hyperabduction. Evidence from other fields suggests
that that this can lead to impingement and other problems in the
A wide variety of explanations have been proposed over the
years to explain Mark Prior's injury problems. These
explanations include poor conditioning, inefficient mechanics,
the effects of other injuries, and gradual changes in Mark
Prior's pitching mechanics over time. While each of these
explanations has its merits, I think the differences that I have
established between the pitching mechanics of Mark Prior and the
pitching mechanics of Greg Maddux and Nolan Ryan suggest that a
simpler explanation may be the correct one; that Mark Prior's
pitching mechanics were never as good as people thought they
were, and that Mark Prior's pitching mechanics are largely
responsible for his injury problems. As a result, I would not be
surprised if the fans of the San Diego Padres find Mark Prior to
be as big of a disappointment as the fans of the Chicago Cubs
have found him to be.
I recently completed a piece that addresses the question of
perfect pitching mechanics.
I was the first person to express concerns about Mark Prior's
shoulder back in late 2005 in my
photographic analysis of Mark Prior's pitching mechanics
It turns out that Mark Prior is
making another attempt at a comeback, so I put together a piece
Mark Prior's New Pitching Mechanics.
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.