Peyton Manning ranks No. 3 among all-time QBs

Jackson: Broncos gave Peyton an opportunity (1:39)

Former Broncos LB Tom Jackson talks about Peyton Manning's time in Denver. (1:39)

My best memories of Peyton Manning, believe it or not, are what happened to him in the 2015 season.

Age, four back surgeries and plantar fascia gradually robbed him of his ability to do so much of what made him great for years. By Super Bowl 50, he was no longer a top-tier quarterback. Nevertheless, the football gods were merciful enough to let Manning go out with a Super Bowl ring and finish his legacy as the third-best quarterback in football history.

It's the ending of Manning's career that forced me to make the tough decision to place him over Johnny Unitas, whom I once rated as the gold standard for quarterbacks. From a historical prospective, the past two Super Bowls redefined my look at the great quarterbacks.

Last year, New England Patriots quarterback Tom Brady passed Joe Montana and Unitas, in my opinion, by winning his fourth Super Bowl in six tries in one of the best Super Bowls ever played. Montana is Montana. He's No. 2.

As we've seen, greatness is usually rewarded. Steve Young shook off criticism for not winning the big game by blowing out the San Diego Chargers in Super Bowl XXIX and getting that monkey off his back. John Elway waited until his final two years to get the Super Bowl titles the Denver Broncos missed in his younger days.

One of the biggest title voids in quarterback history involves Dan Marino, who was one of the most gifted quarterbacks I've ever seen -- he had the arm, the mind and the guts. By his second year, he was in the Super Bowl after posting a record-breaking season for touchdown passes (48).

Marino lost to Montana and never got back to the big game.

That's why Super Bowl 50 and the 2015 season was so special for those like myself who believed in Manning. If you really look back at it, Manning missed only one other sure chance to have a ring. That was in 2004, when the Colts lost in the divisional round to the New England Patriots.

At the time, the Colts were near their peak for talent. But when top teams meet dynasties, misfortune happens.

Ask the Oakland Raiders, whose ultimate success in the 1970s was suppressed by the Pittsburgh Steelers' dynasty. Ask the Houston Oilers, who knocked on the door of greatness but had it slammed shut by the Steelers.

Elway has always said a great quarterback can be 95 percent sure he is at the end, but that last 5 percent is the hardest to admit. Manning faced that reality after last season, when he faded down the stretch. He wanted another year, but he had the best person to judge those desires in Elway, who runs the Broncos.

Elway wouldn't let Manning dictate Manning's return. First, he asked Manning to take a $4 million pay cut. Manning accepted. Next, Elway brought in Gary Kubiak, and Manning had to accept playing in an offense that didn't fit his style.

Manning is a shotgun quarterback who wins with his downfield vision and smarts. Kubiak runs an offense based on the run, requiring more snaps from directly behind the center and occasional rollouts. Seeing Manning roll out is like watching him sing about chicken parm sandwiches in a TV commercial.

Then came the ultimate embarrassment. Kubiak benched Manning after a four-interception game against Kansas City, a week after Manning suffered a tear in his plantar fascia in Indianapolis. The Broncos had enough confidence in Brock Osweiler that they were going to let the young signal-caller carry the team into the playoffs.

Manning took the bad news professionally and began rehabbing his foot injury. He accepted his demotion, showing his respect for the game and the organization, until fate called upon him once again.

Osweiler struggled in the final game of the regular season, which opened the door for Manning to get one more shot. Sure, it wasn't pretty watching him. He strung together a lot of three-and-outs.

By the Super Bowl, his skills had diminished so much that he couldn't even get touchdown drives out of great field position created by turnovers or long returns. Were it not for the last touchdown set up by a turnover, Manning would have been the first quarterback to win a Super Bowl without a touchdown drive.

Instead, he now has won a Super Bowl title with two different teams, a rare feat. Unitas kept pushing and pushing from ages 38 to 40 and won only five of his last 14 starts in his final three seasons. In the last year, he was only a 44.7 percent thrower, a shadow of himself. Joe Namath, 34 but playing on what appeared to be 50-year-old knees, pushed it one season too many by becoming a 46.7 percent thrower for the Los Angeles Rams.

In comparing quarterbacks, the break-off point is 1978. That's when the game changed. Cornerbacks weren't allowed to mug receivers. Flags were thrown if a defender made contact with a pass-catcher after 5 yards. It opened up the game to become a quarterback-driven league.

It set the stage for Montana to become a legend in Bill Walsh's West Coast offense. It allowed Brady to win Super Bowls with any type of creative offense Bill Belichick tried. It allowed Manning to open up offenses to the shotgun and the no-huddle.

I will always treasure the visions of Manning barking out play calls and adjustments at the line. But I will remember most how football finally gave him the proper going-away present with a win in Super Bowl 50.