over the last month or so about Homer’s loss of velocity and its relationship to his shoulder, elbow, arm, etc. But If you’re really worried about a pitcher’s loss of velocity, the first thing you look at is the acceleration of his hips, rather than his shoulder or elbow. Otherwise, you might just be plugging him into an expensive machine for an hour to no purpose.

The shoulder and elbow have far less to do with velocity than do the legs and the legs have less to do with velocity than do the hips. So, when it comes to improving velocity,

Hips>Legs>Arm.

As far as I can tell from reading Robert Adair’s The Physics of Baseball and Dr. Mike Marshall’s work (a lot of which is now online) , this is the current position of most kinetic physicists working on pitching mechanics. Here’s a rough and ready breakdown from Will Carroll’s Saving the Pitcher (which every fan would benefit from reading and owning):

But there is one key part of the pitcher’s anatomy that cannot be out of whack and still allow for success. It is also the reason that a pitcher who looks less like a prototype and more like an average guy or skinny Dominican can have the success that Billy Wagner or Pedro Martinez have…the one talent that every successful pitcher at any level has is the ability to accelerate the hips. Quick: name one drill that teaches this or that seeks to improve this skill. Most pitching coaches I posed this problem to came up blank. That, in a nutshell, is one of the major reasons why at every level we are often failing our pitchers.

(p. 40)

And:

Within this kinetic chain of pitching, the rotation of the hips impart the most energy to the ball….In fact, hip rotational velocity is more closely associated with pitch velocity than any other mechanism in the chain. According to research done by Dr. Gelnn Fleisig, which looked at the force generated by many pitchers during biomechanical analysis, most of the force was generated at or near the hips. “Eighty percent of power is created at the core.”

pp. 42-3

So while it could have something to do with a shoulder problem, it might have nothing to do with his shoulder at all. Not to play armchair diagnostician, but Homer’s velocity problems - if he actuallly has involuntarily lost his velocity - could just as easily be related to his groin problems from last year. If he has become more wary about pulling his groin, he might not be achieving the same speed in his hip rotation. Or maybe his over the head wind-up triggered some sort of energy transfer for him that was harmed by his abbreviated wind-up.

I think we’ve been overly concerned with his Homer’s arm to the exclusion of a number of other things that might be hampering his performance.