I appreciate your comments. My take on this is that "reverse forearm bounce" is a misnomer. The positive part of what's coming out of this thread is that this motion is extremely stressful on both the shoulder and elbow. No big surprise there for anyone. I still maintain that the forearm does not "bounce" back, down and up again. I also maintain that the hand takes a path that loops. Yes, Chris, the motion is fast and puts much stress on the tissues in the shoulder and elbow but the extension of elbow, which anyone would agree does have the potential for stress on the involved tissues, has nothing to do with the term we're speaking of here.
Chris, take another look at the slow motion Clemens clip when he was with Toronto. Although the 90 deg (or thereabouts, maybe more acute with Clemens) angle of the forearm to the humerus is maintained, the path the hand takes is a loop. This is due to the fact that the elbow is coming around as the shoulders turn. The ball is kind of "dragged" back, down, around and up and over toward release. This is the loop I speak of. The extension of the elbow does not happen until the shoulders have completely squared to the plate. Thus, the 90 deg. +- bend does not change until then. At least not in a significant amount.
If we want to talk about "bounce" happening somewhere in all of this, we would need to talk about the muscles and connective tissues of the rotator cuff and the elbow. They are put on stretch rapidly as you, Chris, have pointed out. The UCL takes on an enormous amount of stress in this, as does the rotator cuff muscles and tendons. The "stretch shortening cycle" (SSC) is at work here and actually is a key ingredient in the entire process. By way of generating power, the SSC is vital BUT it comes at a cost, or a risk, should I say.
So, I would agree that there may be "bounce" because of the SSC in these tissues but "reverse forearm bounce" implies that the forearm as a unit goes back and down, then hits a stopping point and "bounces" back up. This is the part I do not believe happens because of the "loop" that takes place. I think this loop is essential in doing a couple of things. It allows the arm action in the pitching motion to steadily increase in tempo so that there are no pause which kill energy transfer and also that it helps to mitigate (not completely eliminate) the stresses put on the rotator cuff.
In conclusion, the stretch shortening cycle for elbow and shoulder muscles and connective tissue, YES, forearm bouncing, NO. As always, my opinion based on observation and much discussion.
Thanks for the discussion guys. I hope that, as we resolve what I believe has become a semantic argument, that some understanding of the stressful nature of this motion is now a little clearer to those who haven't studied as much as others.