Wouldn't he have a hard time seeing over those 6 foot 5 to 6 foot eight linebackers? Sure, he could do it and have success. But as good as he is at both, why take the chance of guy that out-weighs you by a hundred pounds or more smashing you like a pumpkin?!
To state the obvious, I guess it is just what Matt wants to do most and who/what are his best opportunities.
As Coach Church told me one day, "He is one BAD DUDE!" Ha, true that!