The old football adage is: “the most popular guy in town is the backup quarterback.”

Whoever came up with that clearly hasn’t visited the city of Pittsburgh lately.

The first 52 minutes and 18 seconds of Mike Vick’s second start in a Steelers uniform was going so badly that fans on social media were calling for third string quarterback Landry Jones to replace him as early as halftime.

(No, seriously. People really wanted Landry Jones. I wish I made that up.)

Then Vick did something nobody saw coming: he led the Steelers on back-to-back touchdown scoring drives, one to tie the game at 17-17, the second to earn the Steelers a 24-20 win over the San Diego Chargers on a Le’Veon Bell touchdown run as time expired Monday night.

Ben Roethlisberger might take credit for coming up with the play that led to Vick’s game-tying touchdown bomb to Markus Wheaton, and Bell might have scored the touchdown that won the game, but Vick’s strong arm and nimble feet helped put the offense in position to finish the job.

While Vick hasn’t been great, he’s been just good enough to put the Steelers in position to win both games he’s started in, even though one of them resulted in a loss.

And believe it or not, he’s a better backup option than other NFL teams have under center right now.

The Chicago Bears had to face the defending NFC champion Seattle Seahawks on the road with Jimmy Clausen to fill in for Jay Cutler. Clausen completed only nine of 17 passes for a whopping 63 yards in a 26-0 shutout loss.

The Dallas Cowboys are plunging further into the abyss after their second straight loss, and they’re now turning to Matt Cassel instead of Brandon Weeden in place of the injured Tony Romo. (Hey, remember when Jerry Jones told us we would never find a more gifted passer than Brandon Weeden?? Sorry, I had to…)

The Houston Texans still can’t figure out a starter between Brian Hoyer and Ryan Mallett, and in the midst of that indecision they were beaten by Indianapolis Colts’ backup Matt Hasselbeck.

That’s a 40-year-old Matt Hasselbeck who was fighting a viral illness that caused both severe vomiting and diarrhea and subjected him to heavy IV fluid intake throughout the week leading up to game time.

I think you see my point.

There’s a reason why franchise quarterbacks are coveted, heralded, and when they go down with injuries, mourned. Because it’s hard — sometimes virtually impossible — to win without them.

The franchise quarterback has one directive: go out and win games. The backup quarterback has one that’s exactly the opposite: just don’t screw it up.

Every once in a while, you’ll find a rare exception to that rule: in January 1993, Frank Reich led the Buffalo Bills to a historic comeback playoff win over the Houston Oilers after trailing 35-3 in the second half of the AFC Wild Card game, and then beat the Steelers the following week in the Divisional Playoff, allowing Kelly to get healthy again and lead the Bills to their third consecutive Super Bowl appearance.

Late in the 1990 season, New York Giants backup Jeff Hostetler took over for an injured Phil Simms. Hostetler led the Giants to wins in two of their final three regular season games, and through the NFC playoffs to beat Kelly, Reich and the Bills in Super Bowl XXV.

Make no mistake: Mike Vick is not Frank Reich, nor is he Jeff Hostetler. Not yet, at least.

His job isn’t to be a postseason hero or to win a Super Bowl. Right now he’s charged with simply keeping the Steelers afloat until Ben Roethlisberger returns.

He will surely make more mistakes, miss passes, fail to make correct audibles and provide moments that make fans miss Roethlisberger. After all, that’s what backup quarterbacks do. If they played better, they would be starters.

Vick’s days as a starter have come and gone, but he is embracing the role as the willing understudy. And with the help of the injured starter guiding him, a defense that has markedly improved in a season where growing pains have been anticipated and a unique skill set that gives him advantages other backups don’t have, he’s doing just enough right now not to screw it up.

And right now, that’s all the Steelers can ask of him because they know how tough the situation is to overcome.

They also realize that when they look at backups around the league right now, things could be much, much worse.