I think that him playing DE in college as opposed to DT has given people the impression that his floor is low. He was productive as a 300 pound 4-3 DE in college, but he never had that special athleticism to play the edge in the NFL, so they said high floor, low ceiling.
However, his athleticism is definitely above average for the interior. His ceiling is low as an edge guy, but I think it's high as a full time interior guy, playing the 5, 3, and 1 spots. In the NFL, 5 techs play more of a DT role and often slide into the 3 or 1 depending on the formation. He'll excel on the inside. He's quicker than given credit for, and I'll admit I didn't give him enough credit at first.