There is no truth as universally accepted in the NFL as the one that dictates a championship team must have an elite quarterback mostly responsible for the winning.

On the flip side, nothing is more certain to derail the hopes for a Super Bowl as losing that franchise quarterback to injury during the season. Injuries happen, and having one happen to the quarterback is extremely bad luck, but that’s pretty much the end, buddy.

Against that backdrop of truth and consequences, the thousands of words spilled regarding the possible identity of the backup quarterbacks who will fill out the depth chart beneath Carson Wentz for the Eagles this season seem a bit much.

Head coach Doug Pederson has spilled most of them, and all laudatory, whether addressing the play of Nate Sudfeld, Clayton Thorson, Cody Kessler, or, most recently, 40-year-old Josh McCown.

Pederson said what he said because he was asked, and there’s no point in delving into further truths. The potential backups haven’t been all that impressive in practice and the exhibitions — or, more accurately, none have been better than their accepted downsides — but, really, what’s the difference? If Carson Wentz is lost to injury, the tallest tent pole is removed from the big top and then it’s just a matter of whether the crowded clown car can escape before the whole thing falls.

All very pragmatic and logical, and taken without question in 31 other NFL outposts. Here, however, the perspective has to be different, and it is because of that silver football resting in the trophy case as you enter the main building of the NovaCare Complex.

Oh, right. That happened. The backup won the Super Bowl.

It is tempting to dismiss what Nick Foles and the Eagles accomplished at the end of the 2017 season as the exception proving the rule. In the 53-year history of the Super Bowl, only one other backup elevated by injury during the regular season finished with confetti on his shoulder pads. That was Jeff Hostetler of the Giants, who stepped in for Phil Simms at the end of the 1990 season.

Fifty-one other times, the season’s quarterback plan remained in place for the eventual Super Bowl champion.

A final-hour exception could be Earl Morrall’s taking over for an injured Johnny Unitas in Super Bowl V, but Morrall — 7-for-15, one interception, and a 54.0 quarterback rating — hardly qualified for heroism. (The quarterback plans that worked out include the 1987 season in Washington, when the Redskins sorted out a healthy battle between Jay Schroeder and Doug Williams, and a similar situation in Baltimore in 2000 between Tony Banks and Trent Dilfer.)

So, in terms of being able to adhere to the plan, it has happened 96 percent of the time.

Giants quarterback Jeff Hostetler (15) won the Super Bowl as a backup in January 1991.
Olga Shalygin
Giants quarterback Jeff Hostetler (15) won the Super Bowl as a backup in January 1991.

That’s faulty math when it is reduced just to the Super Bowl, of course, and there is no faulty math like sportswriter math. How many times did a backup actually have the chance to win that specific game? Hardly any.

But the better question is how many times did a team lose its starter late in the season and therefore not have a chance to get to the finish line? That would be a larger sample, and it is the hurdle the Eagles and Nick Foles overcame in 2017.

A lot had to go right, starting with Foles deciding after the 2016 season to: (a) not retire, which he seriously considered; (b) leave the Kansas City Chiefs, where he was comfortable playing for Andy Reid behind Alex Smith; and, (c) return to Philadelphia and presumably sit behind somebody else, in this case, Wentz.

Pederson’s selling job might still be the most underrated part of that story. He and Foles had worked together just one season (when Foles was 1-5 as a rookie), but whatever the team promised Foles — aside from the two-year contract with $7 million guaranteed — certainly worked. Otherwise, it would probably have been Chase Daniel trotting onto the field at the L.A. Coliseum that December after Wentz blew up his knee. Imagine that for a moment.

Maybe we’ll look back some day, and the twists and turns in the quarterbacks room during this training camp and preseason will have similar meaning, instead of, well, no meaning at all.

We’ll tell the story of how Pederson lured Josh McCown out of retirement and a comfy chair in the broadcast booth to unexpected glory. Or maybe the story of how Nate Sudfeld came back from a broken wrist to reclaim his co-pilot seat and eventually land the plane in the Super Bowl. Or how smallish Cody Kessler surprised everyone by outlasting his taller rivals to become one of only three Super Bowl-winning quarterbacks shorter than 6-foot-2 in the last 35 years (along with Drew Brees and Russell Wilson). Or maybe how rookie Clayton Thorson suddenly emerged and -- OK, let’s leave that one where it is.

The point is that the story of Nick Foles tells us that unlikely doesn’t mean impossible. Frankly, it is why the quarterbacks angling to back up Wentz get out of bed in the morning. None of them grew up hoping to someday be a substitute. Fortunately or unfortunately, Wentz’s injury history gives them a reason to believe theirs could be the next shoulder tapped by the hand of fate.

That hand fell heavily here two years ago, and if it happened once, it can happen again. Elsewhere in the NFL, that might not be the perspective, but the view is a little different here, starting with the reflection from the silver football in the lobby.