Roethlisberger has ankle injury

ments from the visions of Mike Tomlin’s bread-and-butter game plan.

“We had the Big Three rolling on offense, and we stopped the run on defense,” Tomlin said. “We do those things, we have a chance to win … regardless of circumstance, situation or opponent.”

One game. Antonio Brown turned two short passes into instant points — 50- and 62-yard touchdowns that made it 14-0 halfway through the first quarter.

Le’Veon Bell played in the first playoff game of his NFL career and set the franchise’s postseason record with 167 rushing yards, topping a mark that Hall of Famer Franco Harris set nearly 42 years ago.

Ben Roethlisberger completed his first 11 throws. And the evolving defense limited Jay Ajayi, the runner who stung Pittsburgh for 204 rushing yards during the regular season, to 33 yards while sacking Matt Moore five times.

Still, for all that, there was reason to pump the brakes with caution.

This victory came with warning signs.

Roethlisberger showed up for his postgame news conference wearing a walking boot on his right foot to protect an ankle injury.

The quarterback downplayed the seriousness of the setback, which is believed to have occurred on his last pass of the game — a fourth-quarter interception on which he attempted to make the tackle. He insisted that it won’t keep him out of the game at Kansas City.

Yet it makes you wonder: Why was Roethlisberger still in the game with five minutes to play and Pittsburgh leading by 18 points?

Tomlin didn’t answer that risk assessment; the injury wasn’t revealed until after the coach had addressed the media.

But he readily acknowledged other concerns.

“We weren’t perfect,” he said. “But we haven’t been perfect all year, let’s be honest. It was enough for the victory.”

Sure, the bottom-line result was achieved. The Steelers are moving on. But the first of Roethlisberger’s two interceptions went through the arms of Brown on a pass over the middle. The defense killed two drives with sack-fumbles on Moore, but it wasn’t exactly airtight against deep passes as Miami tried getting back into the game.

As sharp as the Steelers were early in the game, they got sloppy down the stretch.

That won’t cut it as it gets deep in the playoffs. One or two mishaps didn’t derail the Steelers against the Dolphins, but that might get them beat next weekend at Arrowhead Stadium — and almost certainly would if they were to advance to an AFC title game at the New England Patriots.

The margin for error is so tight. If there was a lesson to be learned for the Steelers from a convincing victory, it is that there is still a fine line between advancing and squandering the opportunity to rip through the playoffs as a hot team on a mission. That’s why Roethlisberger bemoaned a lack of details.

He likened the fast start to “a little bit of a false positive,” speaking with more urgency about that than he did in talking about the ankle.

“I mentioned this before the game,” Roethlisberger added. “The ‘ my bads’ are usually not good. You can’t usually correct ‘my bads.’ You can’t have them. It’s just the way it is in the postseason, and I think in the second half we had a little bit too much of that.”

Leave it to Roethlisberger, usually a good measure of the pulse of the team, to put the win in perspective. He has seen the Steelers win a Super Bowl as a sixth seed and then win one playoff game in five years before the latest showing.

He knows. Now is hardly the time to take anything.

“The ‘my bads’ are usually not good. ... You can’t have them.” Steelers quarterback Ben Roethlisberger