Can't believe Sean Lee is already 30. Man time really flies when you're always injured
I was thinking the same thing until I realized that Lee has only been in the league for six seasons, injured or healthy. Turns out, he was already 24 his rookie year. Don't got the story on why, maybe someone else does, but I think this would mean he shouldn't be regarded as a typical 30 year old in the NFL. Perhaps he is more like a 28 years old in terms of NFL "wear and tear".
I don't think age is as much an issue as it should seem because there are so many other factors that influence longevity and lack of.
These would include injuries, from a series of nagging ones to a single devastating one, The position they played would be as factor, I understand the shortest are RB's and NT's. They could include the quality of your team and the way in which that limited exposure to hard hitting tackles or pancake blocks. Simple genetics can't be ignored, some kids are just built Ram Tough, some are made of glass.
There is no doubt Jason Garrett is Ram Tough.
Did everybody know that Roger Staubach didn't play in the NFL until he was 27? Obviously required knowledge, but check this out. He retired at the age of 37 after a season in which he was the #1 ranked QB in the NFL per rating. So why did he retire?
You have to remember that he retired the same year the NFL decided to add new rules that protected the quarterback such as "in the grasp". Before then, defensive players could practically body slam a quarterback.
Anyway, Staubach retired "early" at the age of 37 because he had a bunch of concussions and knew it was getting too dangerous to play.