Well, I am just going on everything I seem to read about him on a variety of football and scouting sites and blogs. In fact I have not found anything differently said about him. Here is an example:
"Despite beginning his tenure at UNC with plenty of fanfare after earning starts in the first three games of his collegiate career, Martin's time in Chapel Hill has featured more flash than dominance. After consecutive four-sack seasons during his sophomore and junior years, Martin totaled 11 sacks in a breakout senior campaign that earned him an invitation to the Senior Bowl. Martin continued his strong senior campaign in Mobile, with a solid week of practice and four tackles (including 1.5 for loss) during the game, itself.
So where was this production earlier? The truth of the matter is, Martin is better against the run that the pass and has been effective in this role throughout his career, averaging nearly 15 tackles for loss a year over the past three seasons. His game is built upon his length and power to control at the line of scrimmage rather than burst or fluidity, making him an ideal base (left) end in a traditional 4-3 alignment."