I could see the argument that Mackenzie's true position is at nose tackle in a 3-4, and that he should be compared against other 1 technique tackles. It would also be a further indictment of Butch Jones that he tried to shoehorn a player into playing against his natural position.
However, the fact is (as you pointed out), that Mackenzie rarely lined up at the nose in college, and wasn't all that effective when he did; he was no more effective as a 1 than he was as a 3. To suggest that one can adequately judge his performance as a 1 technique is insane.
Even playing DT in a 4-3, the guy rarely got decent leverage, almost never reset the line of scrimmage, and didn't eat up blockers. Teams with even above average interior linemen rarely felt the need to double team Mackenzie, allowing centers and guards to get up to the next level to put a hat on a linebacker. If D4H is going to argue that Mackenzie should be judged as a space eater, then by all means... he wasn't very good at it.