The Steelers, once 11-0 and the latest threat to the 1972 Dolphins’ perfect season, are now a threat to become the most disappointing one-and-done team in the playoffs after losing their past three games, the latest to what had been a two-win Bengals team.

So, a lot of eyes are on the 11-3 Steelers on Sunday as they play the 10-4 Colts in Pittsburgh in The Post’s Big Game this week.

A Steelers win would be an indication that perhaps they’re back to form. It, too, would provide some evidence they have a chance to go deeper into the postseason than one game, because the Colts are likely a playoff team as well.

The Colts enter this game on an opposite trajectory to that of the Steelers. They’re hot, having won three in a row and seven of their past nine games. They’re tied with the Titans atop the AFC South, though Tennessee holds the tiebreaker advantages over Indianapolis with two games left.

The Colts are in control of their destiny for a wild-card playoff spot. But a stumble could be costly because they’ve lost to the Browns (10-4) and Ravens (9-5), two teams also in the hunt for a wild-card berth. So, the Colts could have tiebreaker issues with those two teams if it came to that.

If the Colts win their final two games — they finish with the lowly Jaguars — it’s possible they could finish 12-4 and not win the AFC South. Because if the Titans win out, they finish 12-4, too.

Conversely, the Colts could split their final two games and miss the playoffs if Baltimore wins out, Cleveland splits its final two games and Tennessee splits or wins out. It’s very rare that an 11-5 team does not qualify for the playoffs — and would be more surprising this year with an added wild-card team in each conference.

“The way we get to where we want to go to is by worrying about the Pittsburgh Steelers,” Colts coach Frank Reich told reporters during the week. “If we’re good enough, we’ll be there.”

The Steelers are in a crisis of confidence at the moment, not exactly sure who they are and whether they are good enough.

Things have gotten so tense that Steelers quarterback Ben Roethlisberger called a players-only meeting on Wednesday.

“It had nothing to do with the losses,’’ Roethlisberger told reporters, doing his best to diffuse any perception of panic. “It had everything to do with where we are and where we are going.”

The Steelers still have two remaining chances to clinch AFC North division title. They can do it by winning one of their final two games against the Colts or Browns, or by the Browns losing to the Jets on Sunday.

“We’re getting ready to go into the playoffs,” Roethlisberger said. “I had the guys raise their hands. ‘Who has played in a playoff game and who hasn’t?’ Over half the guys haven’t played in a playoff game. It’s important that veteran guys communicate what it’s like. I wanted to reiterate how important this time of the year is. The playoffs are not guaranteed to anyone. It wasn’t a players-only panic meeting. It was meeting we felt was necessary going into the postseason.”

The Steelers offense has failed to produce more than 19 points in each of the past four games, three of which were losses. In those four games, Roethlisberger has thrown six TDs and five INTs.

“You have to find ways to win,” Roethlisberger said. “Good teams do it. We did it even earlier this year. But right now, we’re just not doing it. We have to get back to having some sort of continuity. At the end of games, when you need a play to be made, we all have to be there to make it, whoever’s number is called, and it starts with me.’’

One thing Roethlisberger and the Steelers struggling offense will have to overcome Sunday is an opportunistic Indianapolis defense, which is third in the NFL with 24 forced turnovers.

The Colts defense also is allowing the fifth-fewest rushing yards in the league, which doesn’t bode well for the Steelers, who’ve struggled to run the ball effectively, particularly without their top running back, James Conner, out of the lineup with an injury.

“We believe in our formula of preparation,’’ Steelers coach Mike Tomlin said during the week. “We simply have to do it better. Each week we wipe the slate clean.”