From the many articles I have read, docs I have talked to as well as some who are/were in the arena, there is more than one factor alone.
Outside of trauma, contact and otherwise accidental injuries (Madigral) many of the torn tissue issues can be attributed to HGH and PED use. We all know when muscle is built, it becomes larger and thus, heavier. Much of the use of PED does enhance muscle development and size while weakening connective tissues. The stress on that connective tissue becomes too much and leads to a tear. I cannot say how many times I have read and heard that from the professionals. The docs and the athletes know.
As for specific injuries to pitchers' arms. The main factor, I am told, is that pitchers are "maxing out" on virtually every pitch. That style of pitching didn't exist years ago. I think we all know that. Also, I see a lot of pitchers turning pitches over when they deliver the ball. Make that move with your hand and wrist next time you watch a game and feel the torque in the elbow.
Some of it delivery too. I always said it was a matter of time before Chris Sale would have arm issues. It is said he had a heavier work load. But, that delivery was bound to lead to problems. Look at Carlos Rodon. Part of his success this year (fingers crossed) is the fact he tweaked his delivery which relieved some stress. I still think Michael Kopech overthrows at times.
Tommy John surgery is no big deal anymore. But, you'd be surprised at how many 15, 16 and 17 year olds are having it done. It's kind of scary. It's one thing for a big league pitcher to have an elbow issue. But when kids are going under the knife for TJ like it's nothing, there is a serious problem.
Much of what I said are things I learned directly from those involved.
