You to define stretching. Passive stretching, which I grew up with, where you are in a position and try to lengthen the muscles has been shown to actually cause more muscle injuries than it prevents, unless you have a significant decrease in range of motion. It has also been shown to decrease power and performance during athletic activity.
Dynamic stretching such as monster walks and high knee drills are the best activities to get the muscles ready for athletic performance.
However your overall point that there needs to be a significant overhaul in their off season training is right on point.