I think there's a noticeable difference between off-season training (which is what the Drew League is), versus tier-1 international competition. Especially if we're talking about long-term wearing down of bodies, as opposed to freak accidents.
Ed Davis cost himself the beginning of his Rookie year because he decided to play in a pick-up game with Locals. I'd imagine Drew League goes a bit harder than that ...
And I don't think we heard squat about Davis being disrespectful and selfish.
"That was Nasty right? Cocked that Joint back and banged on 'em." -James Johnson