Pro career aside, he wasn't as good of a player in college.
Let's put his career numbers this way - do you think he's the 4th best scorer the program has had? I don't, and I don't think he's even close. Was he the third best creator on offense we've ever had? I don't, also not close to that ranking. It would be a joke to ask if being 3rd in steals means he's our 3rd best guard defender ever, so let's not even ask that. I think there is a very fair argument for GMac being our best ever at big moments, but does that and stat stuffing as a 4 year starter put him in the pantheon? I say no, because surrounding those big moments GMac had a lot of pedestrian and even bad, inefficient play. His floor is lower than the greats we've already recognized.
When I imagine being able to pick teams for a pickup game of all time Syracuse greats, GMac doesn't make the cut. He's barely in the discussion. Who would you pick him over? Whoever it is, my pickup team will beat you with the guy you picked GMac over.