There was no way he was going to play another year under Petrino, who demanded silence during team meals and barely acknowledged his players when he passed them in the hall.
"I hated getting in my car and coming to work every morning," McClure said. "It just wasn't any fun. I've never seen anything like it. In this game, if you can't have fun coming up here to work and handing out the guys, it can be brutal.
"But," he pointed out, "we're way past that now."
Indeed, they are. Since then, McClure has been part of the greatest run in Falcons' history. Five straight winning seasons. Four playoff appearances. Two division titles. Only New England has won more regular-season games than Atlanta during that span.
No wonder McClure hopes to come back for at least one more season, maybe two.
"I'm still having fun," he said. "I enjoy this team, enjoy hanging out with the guys in the locker room. I don't know what else I would do with my time if I didn't have football."
McClure's linemates have pushed for his overlooked career to get some recognition. There's still some "McClure for Pro Bowl" caps around the locker room, part of a campaign last season that started tongue-in-cheek — right tackle Tyson Clabo knew it would get under McClure's skin — but definitely had a serious side to it.
Well, he's still never made it to the Pro Bowl, and chances are he never will at this stage of his career.
That's fine with McClure, who is perfectly content to be just another nondescript guy in the trenches, barely noticed because all he's doing in his what he's paid to do.
Unlike so many pampered athletes, McClure knows how fortunate he is to still be out on the field at his age, having already earned enough money to be set for life, all while playing for the same organization.
While he still returns to his native Louisiana in the offseason, he's been able to put down roots in Atlanta with his wife and their four children — two boys and two girls, ranging in age from 5 to 11.
"I definitely feel blessed to have been here the whole time," McClure said. "I haven't had to move my family all around the country."
There's just one bit of unfinished business.
"Now," he added, "I think it's time for us to go win a championship."
Follow Paul Newberry on Twitter at www.twitter.com/pnewberry1963