Concussions and tears are part of the game unfortunately but I'll never understand the amount of hamstring injuries league wide. Seems to happen to players even if no history of it in college, it's the same game isn't it? Obviously the NFL is a league on another level, physicality and speed wise, but still these guys have been training to play this sport for years.
In middle school and high school I played football and ran track. During those times I pulled a hamstring one time in 10th grade and it was because I was running late and didn't have a chance to do full stretches with the team. So I blamed that hamstring pull on not stretching.
If you go to a Titans game these days, watch their pregame rituals. The players mingle around with each other, dance to the music playing on the PA system, doing some sort of photo ops or just playing catch. They never stretch as a team like you would use to see back in the day. This could also have a lot to do with the numerous injuries.