There is a lot of information out there suggesting that pre-exercise 'static stretching' is not all that effective, but there is no doubt in my mind that pre-exercise 'sport-specific dynamic stretching' is very beneficial. Dynamic stretching is done in nearly all competitive team sports, and can be seen occasionally in training camp videos being done in a line.
I'm not sure why the injury bug is so prevalent in camp at the moment, but I'm fairly certain that the stretching and preparation being done (or not being done) by the team isn't the issue. I guess it is better to be hurt early in the season than late, but I really hope the team stops getting hurt and starts getting healthier.
"the Quarterback can run if he wants to, but with this rocket attached to your body... who would?" -Aaron Rodgers