I preface this by saying that Peyton Manning is my all-time favorite athlete of any sport and the best quarterback of his generation. He has provided me hundreds of hours of entertainment and hundreds of amazing highlights that have had me on my feet cheering wildly. A Peyton Manning doll given to me as a gag gift is a prized possession. But it’s become obvious even though it pains me to say: He needs to retire.

This became apparent in the wake of the 24-13 loss Sunday by the Denver Broncos to the Indianapolis Colts in the AFC playoffs. Manning has gotten quite old by quarterback years and he simply doesn’t have it in him to play a full season and the playoffs at the level we’ve grown accustomed to. He can still muster the occasional vintage Peyton Manning game but that’s not good enough by standards he has set for himself. Bow out now and don’t be like Brett Favre in 2010, looking pathetic on a struggling team.

I will totally understand if Manning wants to come back in 2015 and he deserves the chance to go out on his own terms. Maybe he simply loves playing the game and wants to do it as long as he is able. Sunday, he would not commit to returning, wanting to see how he feels and what moves the organization might make. If injury was a reason for his erratic play recently, he might want a chance to start fresh and give it another run. If so, I will be his biggest booster, hoping he can defy age. Deep inside, though, I know his window to win a second Super Bowl is shut.

Age is the brutal leveler in the NFL and Manning will be 39 1/2 by the time the 2015 NFL season starts. At 38, John Elway was oldest quarterback to win a Super Bowl and no other quarterback older than 37 has even played in one. He is still better than a handful of NFL quarterbacks, but that’s actually a comedown for him and his better days are clearly behind him. Another ring ain’t happening. A division championship maybe, a wild card win perhaps. But not the Super Bowl and that’s always the measure by how a Peyton Manning season is judged.

It wasn’t just that the Bronocs lost to the Colts, but how they did. It was his biggest home playoff loss ever. Two years ago, in another first-game playoff loss, the Broncos fell to Baltimore 38-35 in double overtime but Manning at least made it a great game; one that turned on a 70-yard TD miracle by the Ravens in the final seconds of regulation when Manning had gotten Denver a touchdown lead. And while last season ended in a debacle against Seattle, at least that was in the Super Bowl and one game after he threw for 400 yards against the Patriots.

Sunday was just sad. After scoring a touchdown on their first drive, the Broncos could muster only two measly field goals the rest of the way. Denver had four three-and-outs in the second half, all coming when the game was still very winnable. The Manning of 2012 scores on two of those drives and maybe gets the win. The Manning of 2009 wins that game by two touchdowns. But an additional 36 games have passed since the end of the 2012 season and age and injuries have taken their toll. He can still make some marvelous passes but too often on Sunday were scenes of him flinging it deep with little chance of a completion. This stat says a lot: In the first 12 games of the season he threw 36 touchdowns and nine interceptions. In his last five games he had four touchdowns and six interceptions.

He has been banged up, but injuries are more frequent and lingering with older players. I wonder if the concern about getting hurt is why Manning did not try to run for what would have been a big first down in the third quarter, instead throwing an incompletion. Not that I blame him, but it seemed a tentative decision when boldness was needed.

There is no shame in him hanging it up now. His legacy is secure and he will be a unanimous first-ballot Hall of Fame selection. He saved the Colts from moving from Indianapolis and made the Broncos relevant again for the first time in a decade. He is the single most important NFL player of the last 16 years and the most popular. No one in the sport has a bad word to say about him and I would hate to see it end for him in some meaningless Week 17 game next season with the Broncos playing out the string.

He has played for two horse teams during his career, so it’s time for Peyton Manning to saddle up a colt or a bronco and ride off into the sunset.