Why can't baseball pitchers stay healthy?
For the same reason they are throwing harder.
Because pitching coaches and velocity trainers are increasingly employing a number of Tricks & Shortcuts -- starting with what I call the Big Five, including the Tommy John Twist -- that yield quick and easy velocity boosts.
That work by overloading the pitching arm.
By creating what I call Timing problems.
Increasingly, that is leading pitchers to develop Blood Clots, not just the standard elbow and shoulder problems.
Which is terrifying.
Or should be.
As @Econtalker teaches, there's No Free Lunch.
Over the past 15 to 20 years, pitching coaches have discovered a number of tricks and shortcuts that quickly deliver pitching velocity increases -- and that allow pitchers to throw harder, at younger ages -- by pushing pitchers' mechanics and arms to the limit.
And, increasingly, beyond it.
My presentation about the epidemic provides an overview of the problem, its root cause, and the solution. For best viewing, download the PDFs of my presentations to your computer (right click then Save File/Link As...) and open them from there...
Want to know how I judge Timing in pitchers? Want to do your own study of the impact of Timing on pitchers' health? Here's some insight into my methodology for judging Timing.
Given that The Epidemic deals with the topics of Tommy John surgery, Thoracic Outlet Syndrome, pitching injuries, and injury prevention, most of it is accessible for free. However, because this is what I do for a living, and how much time I have invested in this project, the more important sections, which are marked with 
are only available to clients who purchase access to The Epidemic. or one of my other pitching webbooks.