SAN FRANCISCO — Peyton Manning isn’t the player he once was, but he somehow has made it back to the Super Bowl for what could be his final NFL game at age 39. Former NFL quarterback Boomer Esiason, who lost to Joe Montana in Super Bowl XXIII, said Manning has summoned every ounce of physical and mental energy to get this far, likening him to another aging athlete who recently played for a championship.

“He’s the Bartolo Colon of the NFL, although [Manning] is in much better shape than Bartolo,” Esiason said, comparing him to the husky 42-year-old pitcher who helped the Mets get to the 2015 World Series, where they were beaten by the Royals.

“[Manning] has learned to throw junk,’’ said Esiason, a star lefthanded pitcher for East Islip High School who went 15-0 in his senior year in 1979 and won the Carl Yastrzemski Award as Suffolk’s top player. “He’s learned how to make the right calls at the line of scrimmage. He’s learned how to deal with all the situations, because he’s sharper [mentally] than anybody on the field.”

Asked about the comparison to Colon, Manning had never heard of him. When told that he is an athlete who now relies more on his guile than his physical ability, Manning agreed with the idea.

“There is no question my role has been different this year,” he said. “I’ve played quarterback different than the way I’m used to playing. I haven’t been 100 percent healthy all season. Can’t make some of the same throws, do some of the same things I used to. But I can still move the chains.”

Manning then quoted from country singer Toby Keith’s song, “As Good As I Once Was.”

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“Kind of like Toby Keith said, ‘Maybe I’m not as good as I once was, but I can be as good once as I ever was,’ ” Manning said. “That kind of makes sense. It’s different. I think one thing that’s helped me is that I’ve been flexible. I haven’t been stubborn by saying, ‘This is the only way to do it, the only way to call plays, the only way to make this throw.’

“I’ve learned from different coaches. I’ve had five different head coaches in my career, different offensive coordinators. Being flexible, being able to adjust to a new physical state these past few years, has helped me. It’s a big reason why I’ve been able to function, playing with some different coaches.”

Esiason hopes Manning can play well enough to make it an interesting game against the Panthers on Sunday in Super Bowl 50.

“What I hope as a broadcaster doing the game on TV and radio is a really good game like we got [last year] in Super Bowl 49,” Esiason said. “I don’t want to see what we got in 48, because if that happens, it’s like everybody loses interest, no matter how well Cam [Newton] plays. I hope Peyton can keep it close.”

Last year’s Super Bowl, won by the Patriots, 28-24, wasn’t decided until the final seconds, when the Seahawks’ Russell Wilson was intercepted in the end zone by Malcolm Butler. The year before, Manning’s Broncos lost to the Seahawks, 43-8, at MetLife Stadium.