Check out the highlight photos from the Divisional game against the Broncos. The Broncos defeated the Steelers 23-16 on Jan. 17, 2016.
The goal was to win the Super Bowl, as always, and it was one tight end Ben Roethlisberger thought was within the Steelers' reach this season.
"I think that's what makes today disappointing, because I think we all felt in here that we had a legit opportunity to do that this year," Miller said.
The day after Broncos 23, Steelers 16 was a time for reflection at the UPMC Rooney Sports Complex, and for appreciation of the team the Steelers revealed themselves to be on the way to and throughout Sunday's season-ending loss in Denver.
"I feel like this team, collectively, we thought we could beat anybody, anywhere any time with whoever is in our uniform," Miller said. "I think we proved that throughout the year and to an extent we proved that (in Denver).
"That's what's disappointing."
It's a feeling every team strives for every season, Miller said, and one the 2015 Steelers perceived as real.
"You just have a feeling amongst a group of guys," Miller continued. "We all believed in each other. That's the mark of a real team. You get that feeling going through trials together and coming out the other side, sticking together as a group.
"I think we did that this year."
The trials the 2015 Steelers experienced began when they lost kicker Chris Boswell for the season in the preseason opener on Aug. 9 in Canton, Ohio, and continued through Sunday, when they battled the Broncos without wide receiver Antonio Brown and running back Le'Veon Bell, among others.
Somewhere in between, Miller sensed belief had taken hold.
Photos from the last matchup vs the Bengals at Paul Brown Stadium on December 13th, 2015.
"Maybe that Cincinnati game at their place (a 33-20 victory on Dec. 13 at Paul Brown Stadium), just the way we came together as a group and fought together," Miller said. "It wasn't about individuals. It was about getting the win.
"For me, at that point I knew we might have something special."
Miller knows that when he sees it. The Steelers went to three Super Bowls and won two Vince Lombardi trophies beginning in his rookie year in 2005 through 2010.
Their 18-16 playoff win on Jan. 10 at Cincinnati was the first for the franchise since the 2010 AFC Championship Game and, perhaps, Miller allowed, an indication something special this season might translate into something even bigger and better next season.
"I would hope so," he said. "Especially defensively, those guys played really well down the stretch for us, kept us in the game (in Denver) and I'm encouraged. There are a lot of talented players on that side of the ball, as well as our side of the ball.
"That's the thing to be excited about."