Read the book TB12 Method (I know I know, but it was an interesting book). Most injuries happen because the muscles or tendons are tight and when you work out/lift weights they get tighter and denser and then they rupture. When you are a baby you are like Gumbie, think of how flexible you were and how you lose that flexibility more and more as you get older. Players need to work more on flexibility and pliability. I honestly can't believe Brady did what he did for as long and nobody has tried to replicate that since.
Additionally, there are certain imbalances that lead to injuries. Everyone works out their quads (squats, lunges, running forward) but how many people work their hamstrings equally as much? You work the front of the muscle but not the back. It's a give and take relationship, ying and yang, and that's why there are so many hamstring injuries. It's pretty common sense. If you work the flexion you have to work the extension equally to keep them in balance.