I was reading an article the other day and the studies were showing that the stress on a normal persons UCL at only 80 MPH should be enough to snap it in half. The reason most pitchers don't drop like flies now is because they train and develop that ligament to take more stress. But, as you can see, there's still more and more pitchers going down to this same injury every year. Why?
Honestly, just my own crazy opinion with no real numbers to back it up, I think that pitchers, because they know there is a TJ surgery out there that will fix them if they break and very likely get them back healthy again, are not as considerate of how they should be training their arms really early in their life and instead of being cautious and slow in their development aren't holding anything back when they're learning to pitch in little league and high school baseball. Look at how many high school arms are out there throwing 95 MPH at 17 and 18 years old and putting insane amounts of stress on their arms while they are still physically maturing, and many times having TJ surgery before they even go to college. Why do all the crazy arm exercises every day when you can sign a massive multi-million dollar bonus and just have surgery in a few years?