For your dissection and suggestions...

Yeah, I can see the "catcher" in his action. He stands up. He could use a bit more stride length and bend on the front knee and he could carry his momentum further down the line before he rotates around his body. I think this would also allow for a bit more of a natural release point instead of almost straight over the top.
(BTW, I do realize that some P's are plenty successful with a more upright posting against a more straight front side.)
By the looks of those feet, he's gonna be a big one. That will certainly work in his favor as a P.

Stride length is one of the things I have been trying to get him to work on.

I think part of the problem with that is he spent the 13U year playing on mounds with dual rubbers. One rubber set at 54' - one at 50'. Whenever he would stride properly, his heel would land on the front rubber. Now he is often on mounds that have the rubbers set at 60' and 54', which gives him a little more room.

Then, I think the next step is to get him keep his shoulders closed a little longer and rotate more out over the front leg. Well - that's my plan anyway.

As for the feet... He is now a size 13. Same size as I wear. Of course I'm 6'3 and he is only 5'5. His hands are just as big as mine too. It's kind of funny really. I figure eventually the rest of him will catch up.