Better Lower Half

I am going to guess that the don't see any separation (or torque) between his hips and his shoulders. 

Here is a picture of Tim Lincecum.  You can see the separation between his hips (open) and shoulders (closed).  http://bleacherreport.com/arti...elf-in-time-for-2013

That's my guess. Good luck. 

Yeah, I'd agree that he's not getting a lot out of his lower half.  And the two areas that stand out to me is his short stride and as Golfman mentions, there's not much "separation" (the angular difference between the alignment of the shoulders and hips at the beginning of the forward motion of the throw).

Take a look at these can compare:

http://www.youtube.com/watch?v=fTi6fQ22sH0&feature=player_embedded

http://www.youtube.com/watch?v=KWr41z6k7oM

http://www.youtube.com/watch?v=nmRkF2fGY0A

http://www.youtube.com/watch?v=Ub0DIOkqZ5c

Thanks Golfman and Truman.

I showed my son the videos and we simulated the separation that these major leaguers do so well. He could really feel the tourque you guys talked about. Are there any drills that can we can do to help get this separation in his muscle memory?

BTW: Truman- you must be a Giants fan!!

Good guess  . . . yes, I'm a Giants fan.  But then, I don't feel you're going to find a staff of pitcher's to use as examples any better than what the Giants have had.  And I feel that has a lot to do with their pitching coach Dave Righetti.  It was Righetti that convinced me that my son got it right when he commented so positively on my son's advanced mechanics when he was drafted by them out of high school.  And the thing that I feel was key to that was working on those things that the Hershiser Drill does.  So, I highly recommend this drill as an important starting point that tends to address a lot issues for HS pitchers (see below)

http://www.youtube.com/watch?v=zu4vLOEthM4