Training to throw a baseball harder
So my youngest brother is graduating high school in a couple weeks and making the jump up to college ball. He's an outstanding and talented player and a great athlete. He's a big kid (both naturally and from working out) and really strong. His weakest point however is his throwing. He's not a pitcher or anything, but he needs to simply start throwing harder. Obviously he practices a lot, does long toss, is working on his mechanics, etc; BUT I'm curious - what are your experiences and suggestions from a training perspective as to what he can do in the weight room to specifically improve his throwing?
His college coach (he's already committed to a school) has suggested my brother quit pressing and going overhead with lifts to loosen up his arm a little bit more (he said having overly muscular shoulders wasn't beneficial for ball players - I strongly disagree). I was thinking about just adding an enhanced shoulder routine in his warmup (maybe something like Diesel Crew's) and still have him train as usual (I still have him in a linear SS type progression on PL and Oly lifts - he does sprints and an occasional GPP type workout too).
Suggestions for helping him throw harder? I'd love to hear any other sport specific considerations/training ideas you have too.