Another thing sort of about Carr that I found on SI.
Different players talking about big hits:
Dolphins Defensive End, 6'6", 255 pounds
"On a blind-side hit you can unload all your frustrations from that week or day. But the league will fine you for hitting a guy too hard, and you can't hit a quarterback with your helmet. You have to hit him with your chest, and you can't hit him below the waist. You have a narrow range. In David Carr's first NFL game I had a great shot at him, and I was going to try to really hit him. I figured I wouldn't get fined for hitting a rookie. But he jumped right back up after I hit him, and I was the one who was woozy.
I've also gotten totally nailed by offensive linemen. Once I was blocking for [Dolphins linebacker] Zach Thomas, and I stuck my head out a little bit and got knocked out cold. I used to trash-talk when I was young and didn't know what I was doing, but now I just shut up and play."