I disagree only because I believe the Bills truly thought with the addition of interior lineman they had what they wanted for their line and addressed another major need the pass rush. However, as we now see, Walker couldn't handle the left side and injuries have not helped.
I agree he is a tweener, but guys like Freeney and Dumervil were also considered tweener's and having success rushing the passer. Lack of playtime and the holdout have not helped in this area so far.