"It's tough to go out like that," Smith-Schuster said after the game. "I got tackled, I fumbled, game over. I was just trying to get down. They made a good play."
Smith-Schuster appeared devastated in the postgame locker room, sitting quietly in his chair in full uniform while teammates got dressed and prepared to leave. Quarterback Ben Roethlisberger came over to talk with him during that time.
Teammates were fully supportive of Smith-Schuster after the game, noting his key contributions throughout the season.
"He's been great," wide receiver Antonio Brown said. "He's a reason we're here."
Smith-Schuster, 22, continued to be critical of himself Monday, even after a game in which he had 11 catches for 115 yards -- becoming the youngest NFL player ever to reach 100 receptions in a season, according to ESPN Stats & Information.
When I'm at my lowest, I'm not going to hide. I'm sorry. That loss was on me. I let everyone down, it won't happen again. pic.twitter.com/amLOGJxino— JuJu Smith-Schuster (@TeamJuJu) December 24, 2018
Roethlisberger said on "The Cook & Joe Show" show Monday that he's proud of Smith-Schuster and "hate that it happened to him."
"And told him that, 'If you play this game long enough, JuJu' -- which I think he will, because I think he's a special talent, a special player -- I said, 'You're gonna have many, many more opportunities to go win games and there will probably be a few where things don't go your way,'" Roethlisberger said.
"I said, 'What's gonna happen though is you can make one of two decisions moving forward. You can learn from this, get better, put it behind you and learn from it, or you can dwell on it forever and never be the same receiver.'
"Really, he's one of the main reasons we even had a chance to win that game and win so many games this year. He's a special young talent. I was heartbroken for him. That was one of the worst things about that loss, for me, was him."
With the loss, the Steelers dropped out of first place in the AFC North for the first time since October. To win the division title, Pittsburgh (8-6-1) needs to beat Cincinnati on Sunday and have Baltimore (9-6) lose at home to Cleveland.
If that doesn't happen, the Steelers would need the unlikely scenario of an Indianapolis-Tennessee tie to earn a wild card.
"All we have is a chance," Cam Heyward said. "We just have to go play Cincinnati this week and get a win. You never know what can happen."
ESPN's Jeremy Fowler and The Associated Press contributed to this report.