We are finding more impressive ways to build muscle...our evolution of ligaments can't handle some of the activity we do with said muscles.
The main idea is that a fatigued athlete is far more likely to be injured than a fresh/strong athlete. If a football player has a poor training regimen and is weak or out of shape then they are more likely to be injured on the field. Not the other way around that they are training so hard that the muscles are too strong for their body.
This idea that a muscle is ripping a ligament or a tendon off a bone is pretty damn rare. Only in the event that someone is taking steroids is it really possible for a pure muscle contraction to tear something. The body has built in defense mechanisms from shit like this from happening, one of which specifically being the golgi tendon organ.
The majority of non-contact injuries in the NFL are from players taking a wrong step, like putting all of their weight dynamically through running on a torsioned knee. Think of an RB making a quick cut.
The main aspect with injuries in the NFL is that players are bigger, faster, and stronger. A 250 lb guy running a 4.4 forty lowering his head and hitting you with the crown of the helmet can
quite literally 'hit like a truck.' Or when these LB's reach out to arm tackle an RB and the guy runs right through the arm tackle and tears the defender's pec.