ENGLEWOOD, Colo. — Everyone knows the incredible odds the Philadelphia Eagles overcame when a backup quarterback, Nick Foles, carried them to their first championship in the existence of their franchise.

Unbelievable, right?

Once in a lifetime, right? Not so fast.

What most people don’t realize is that has been commonplace for a few years now.

Get this, the past three Super Bowl winners have all had significant contributions from their backup quarterback.

Not just catching a pass here or there as a trick play, either, but actually making multiple starts.

The old belief that a team’s season goes down the toilet if their quarterback goes down can, well, go down the toilet. Want proof?

Start with the 2015 Denver Broncos.

The great Peyton Manning started the season as the team’s quarterback and ended the season — hosting the Lombardi Trophy — as the team’s signal caller. But don’t forget about ol’ Brock Osweiler.

Coming off the bench when the team needed him the most — after four interceptions from Manning — Osweiler not only carried the team the next seven starts, he provided better quarterback play than Manning had during the start of the season.

Without Osweiler’s 10 touchdowns to six interceptions during that eight-game stretch, the Broncos third Lombardi Trophy would likely only exist in their dreams.

The next season, the same thing happened. This time, with the Broncos’ cross-country rival, the New England Patriots.

With Tom Brady at home for the first four games of the 2016 season, thanks to Deflategate, a young strapping backup by the name of Jimmy Garoppolo — now the second-highest paid player in the league’s history — came in and did his best Brady impression on the field — throwing four touchdowns to no interceptions and racking up two wins before getting injured.

The next two games of Brady’s suspension, and with Garoppolo sidelined with an injury, the Patriots went 1-1 with third-string quarterback Jacoby Brissett.

When Brady was initially handed the four-game suspension, many believed the Patriots were doomed. Instead, a 3-1 start with two backups quarterbacks was the beginning of their 2016 Super Bowl winning season.

Then, it happened a third time in a row.

When MVP-candidate Carson Wentz tore his ACL and LCL after an 11-2 start last season, the country looked at the Eagles and said, ‘Too bad; maybe they’ll be in the running for the Super Bowl next year when Wentz is back.’

Super Bowl MVP Nick Foles had something to say about that.

Okay, maybe the Broncos aren’t in Super Bowl contending mode coming off a 5-11 season — at least that’s what Vegas highly suggests as they have 40-to-1 odds to win the whole thing in 2018.

But look no further than the Broncos new current quarterback, Case Keenum, to find out just how important backups can be for teams fighting to win their division and make playoff runs — a position the Broncos could very well be in this year.

Last year, after Minnesota Vikings’ starting quarterback Sam Bradford was injured after the first game of the season, Keenum came in and lit the league on fire.

In Keenum’s 14 starts, the Vikings went 11-3 and clinched a first-round bye as the NFC’s No. 2 seed thanks in large part to Case’s fantastic play — 22 touchdowns to only seven interceptions. The Vikings, led by a backup, made it one game away from the Super Bowl.

So, what does this all mean for the Broncos in 2018?

Well, for the first time in many years, Denver doesn’t have a decision to make regarding their quarterback position. The starting quarterback, that is.

With Keenum firmly etched in as the starter, there’s a wide open competition between Paxton Lynch and Chad Kelly on who will be his backup.

Through the first week of camp, according to the coaching staff, the door is still wide open.

To many, the battle for the backup role has become almost a joke to gloss over. But if the Broncos have any hopes of contending — whether that be for a Super Bowl, the division or the playoffs — history would say that position could very be crucial in determining whether or not the team is competitive.

When it comes to the most important position battle during camp, forget about the starting positions up for grabs such as third corner, running back and tight end, it’s all about the (backup) quarterback.