In case you're too young to remember, McMahon was Johnny Carson's loyal sidekick on the Tonight Show. Everybody liked him as he sat on the couch, but there was no doubt who sat in the star's chair.
McCoy has been a likeable star the past four years. But the Johnny role has been played by Tim Tebow, Sam Bradford, Mark Ingram and other teams besides Texas.
Try as he might, Colt McMahon hasn't been able to headline the show. That makes the BCS championship game the ultimate legacy-maker.
McCoy almost won a couple of Heismans. McCoy almost won a couple of national championships.
Will the real McCoy please stand up?
He's had a real fine career. But if he loses Thursday night, McCoy will join Alydar and Susan Lucci as the greatest No. 2s in history.
Alydar has been nominated for 21 Daytime Emmys for his work on All My Children. He's won once. Lucci lost the 1978 Triple Crown by a nose, a nose and a nose to Affirmed.
Or was it the other way around? When you're in the Near-Miss Club, all members have the same image.
Heck, you could make the argument McCoy is the second-best No. 12 on his team. That would be safety Earl Thomas, who will undoubtedly make a good pro.
The Alabama game could be McCoy's last shot at image enhancement. The thought of being Colt Lucci is enough to make McCoy do seemingly uncharacteristic things.
"I really don't think with Colt, as positive as he is, I don't think he would use a negative to motivate," Mack Brown said. "I think he would want to be the national championship quarterback a lot more than he would relish being angry because he didn't win something."
McCoy is undeniably positive, but there's nothing wrong with turning negatives into emotional fuel. He certainly has enough to choose from.
Despite a 45-win career and all the passing records and Johnny Unitas and Davey O'Brien awards a quarterback could ever want, he's been denied the Big One. What's worse, the impression is he got shafted out of the Big One.
If not for a last-second mini-miracle TD pass by Texas Tech, the Longhorns probably would have played in last year's BCS game and McCoy would have won the Heisman.
This year he led Texas to an unbeaten season, and all he had to show for it was a third-place Heisman finish.
"I'm completely over that," he said. "I think I was probably more disappointed last year than I am this year because I have so much left to play for."
I think he's over the Heisman like Al Gore is over the 2000 presidential election. Kirk Bohls, the sports columnist for the Austin American-Statesman, didn't vote for the hometown hero.
He explained his reasoning in the paper. A few days later, McCoy was in Orlando for the college football awards show.
"Tell Kirk Bohls thanks for the vote," he told reporters.
Mr. Positive has been diplomatic this week about his near-misses. There's no doubt McCoy's first goal is a national championship. But if that makes a few people re-think their opinion of him along the way, all the better.
When Reggie Bush beat Vince Young for the Heisman in 2005, Texas offensive coordinator Greg Davis sent his quarterback a consoling text message.
"Game on," Young texted back.
When Mark Ingram left McCoy standing in the Heisman Bridesmaids aisle this year, Davis sent the same message.
"Game on," McCoy responded.
In case you don't recall, Young upstaged Bush and the underdog Longhorns beat No. 1 USC to win the national championship.
It's all so déjà vu.
"I answered the way I felt," McCoy said of his response to Davis.
It's the last chance to get off the couch and into Johnny's chair.