There is no all encompassing evidence to tell us how many pitches in a game or season is "too many." I had a long conversation with an Orthopedic Surgeon who has done quite a few sports related surgeries, and now specializes in sports related injuries. I know, take that for what it's worth. He told me most new studies, and his own personal experience, suggests many injuries are set in motion early on in a pitcher's career- and I mean real early. Little League, High School, etc. Improper mechanics, throwing too many curve balls (especially if thrown incorrectly), pitching when your arm is sore, etc. All of that eventually catches up. The next most important factor, again in his opinion, is pitching with a tired or sore arm. You now make corrections you're not even aware of in your delivery and problems result. Finally, for lack of a better word, some guys really do have a "rubber" arm. Different people can handle different levels of work load. With all that said, it makes sense to limit pitches of younger players. There's little evidence that limiting pitches in and of itself has much of an effect on preventing injuries, but it can't hurt. To answer the question, I think Sheets and Sabathia can routinely get up to 110-120 pitches as long as they're not laboring. How can you tell? Fast ball speed, knowing from experience (in the case of Sheets), problems locating pitches, etc. Above all else, pitchers need to eliminate the "macho" approach and be honest with themselves when they start to feel tired- or worse yet...sore.