Can someone explain why Haynesworth says he "can't" play well in a 3-4 D?

What is it about 3-4 that is so different from4-3 that makes it so hard for him to play? Hes a defensive lineman. His position is not that mentally challenging. Rush the passer or stuff the run. As far as I can tell his ability to play shouldn’t be driven by the type of D they are running.

I’m sure there are nuances i don’t understand though. What are they?

In a 3-4, at nose tackle, he’s going to eat a lot of double teams. The job there is mostly to be big, and occupy blockers so the linebackers are free to make the tackles. More taking hits.

In the 4-3, he’s got a little more freedom to rush the pass or stuff the run. Not as likely to be double-teamed. More giving hits.

Hmm makes sense I guess but I don’t understand why he can’t adjust to that. Is he not big enough?

I’m sure he’s exaggerating in saying that he “can’t” play well in a 3-4. He would be quite well suited to playing end in a 3-4 more than nose tackle I think. His run blocking would be good enough but I think he sees himself as a guy who will push the gaps and penetrate. 3-4 linemen simply don’t do a lot of penetrating. At times they will but more often their job is to occupy blockers. A lot of people think it’s hyperbole when they hear that guys like Casey Hampton are double-teamed all day but they really are on running plays. On passing plays it’s more confusing, the offense has a lot more tricks they can use to take them away from the play. There’s no doubt that his numbers won’t look as good in a 3-4. It’s the linebackers who benefit most from good d-linemen. Really the ends in a 3-4 are like defensive tackles and the Nose is like a fire hydrant in the middle that the other team is forced to run around because they can’t go through it.

He’s plenty big, he just doesn’t want to play that role. Think it’s a ego/lazyness thing.

And numbers, which count for a lot at contract time.