Pitching Mechanics Analysis
Scott Williamson

2/20/2008

Scott Williamson is a pitcher who, like Mark Prior and Kerry Wood, started out with tremendous promise but whose career was derailed after two years by arm problems. That includes Tommy John surgery after his second year and shoulder problems more recently. Let's see if we can figure out what happened.

Arm Action And Timing

A pitcher's arm action and timing are the primary determinants of the long-term health of their arm, so it's always the first thing I look at. As the clip below demonstrates, Scott Williamson's arm action is problematic.

Scott Williamson

The issue is that, like Chris Carpenter, BJ Ryan, and Kerry Wood, Scott Williamson has a major Inverted L in his arm action. This ruins his timing and is the root cause of his elbow and shoulder problems.

Scott Williamson

You can see Scott Williamson's Inverted L at Frame 30 of the clip above.

Scott Williamson's Inverted L

Scott Williamson's Inverted L is easier to see in the still photo above. The thing to notice is how his Pitching Arm Side (aka PAS) elbow is at the level of his shoulders and his PAS forearm is hanging down vertically beneath it. This will increase the distance over which, and the force with which, Scott Williamson's PAS upper arm will externally rotate, which will put significant stress on both his elbow and ultimately his shoulder.

Overall Pitching Mechanics

Now that I've given you an overview of Scott Williamson's arm action, let me get into the details of his overall pitching mechanics. 

Scott Williamson

I'll do this using some individual frames from the clip above.

Scott Williamson - Frame 11

Scott Williamson starts out pretty nice. Notice how in Frame 11 he does a good job of getting his hips moving sideways toward the target through the top of his leg lift, which will increase his linear momentum.

Scott Williamson - Frame 22

Scott Williamson also has a nice stride. Notice how in Frame 22 he is leading his stride with his Glove Side (GS) butt cheek, which helps to keep his hips closed as long as possible.

Scott Williamson - Frame 24

Scott Williamson - Frame 25

Scott Williamson - Frame 26

Scott Williamson - Frame 27

Scott Williamson - Frame 28

Frame 28 is where Scott Williamson starts to go off the rails. He breaks his hands in a fairly standard manner, dropping his Pitching Arm Side (PAS) hand to behind his PAS butt cheek. However, he leads with his PAS elbow out of this position, which causes his PAS elbow to get quite high and ruins his timing.

Scott Williamson - Frame 29

Scott Williamson - Frame 30

In Frame 30, notice how Scott Williamson's PAS elbow is up at the level of his shoulders and his forearm is hanging down vertically beneath it, forming the shape of an Inverted L.

Scott Williamson's Inverted L

Scott Williamson's Inverted L is easier to see in the still photo above, which represents the same moment in time.

Scott Williamson - Frame 31

In Frame 31, Scott Williamson is starting to externally rotate his PAS upper arm while his PAS elbow is still at or above the level of his shoulders.

Scott Williamson - Frame 32

Frame 32 represents the moment when the damage is starting to be done to Scott Williamson's arm. Notice how his GS foot has planted and his shoulders have started to rotate but his PAS forearm is horizontal rather than vertical. This, combined with the fact that his elbow is bent 90 degrees, will increase the distance over which, and the force with which, his PAS upper arm will externally rotate. This will significantly increase the load on both his elbow and shoulder.  

Scott Williamson - Frame 33

Scott Williamson - Frame 34

The thing to notice about Frame 34 is that Scott Williamson's PAS forearm is only now in the vertical, high-cocked position. However, his shoulders have rotated 30 or so degrees. This will increase the load on both his elbow and shoulder.

Scott Williamson - Frame 35

Scott Williamson - Frame 36

Scott Williamson - Frame 37

In Frame 37, you can see that Scott Williamson does one last thing that is problematic. Notice how he locks his GS knee through the release point. While this probably does give him a small velocity boost, it certainly puts a significant amount of stress on his knee and hip joint and may increase the stress on his shoulder and elbow. If you study great, durable pitchers like Greg Maddux, while they firm up their front side, they do not lock their GS knee.