He's the gritty outside linebacker who rarely has an off game. He's thoughtful and emotional.
"He's the perfect teammate," safety Stephen Obeng-Agyapong said.
On Saturday, seven minutes into the second-to-last game of his collegiate career, he was in tears.
Mauti was carted off the field in the first quarter of Penn State's 45-22 win against Indiana on Saturday. The senior fell on a short Indiana rushing play, then never got up. A lull swept Beaver Stadium as trainers examined Mauti's left knee, then hauled the 6-foot-2, 232-pound linebacker onto the green cart.
Penn State did not announce the scope of the injury, but Mauti did not return to the field until the fourth quarter. He sat on the sideline, sporting sweat pants and crutches.
"I feel sick," said defensive coordinator Ted Roof, whose eyes watered up as he talked about the senior. "I love that kid."
Said O'Brien: "I've coached a hall of fame quarterback and hall of fame receivers. And he's one of the most special players I've been around."
Mauti, a Butkus Award candidate, leads Penn State with 96 tackles, three interceptions and three forced fumbles.
Teammates who talked to Mauti after the game described the senior as "sullen" and "quiet."
The Louisiana native, son of a Penn State letterman, missed his sophomore season with a right anterior cruciate ligament (ACL) tear. Four games into last season, he tore the ACL in his right knee.
"If I had a knee to give him, I definitely would," linebacker Gerald Hodges said.
After the game, when Mauti linked arms with his teammates in the end zone to sing the alma mater, the student section began to chant his name.
The NCAA sanctions allowed any Penn State player to transfer with no penalty. Mauti, an NFL prospect, stayed. And then he texted, called and met with his teammates.
"As many as he could," said linebacker Mike Hull, who said he was "50-50 on whether to transfer" when the sanctions came out. Hull and Mauti spoke on the phone countless times over the summer.
Mauti, who has a soft southern drawl and slick shoulder-length brown hair, is somewhat of a celebrity on Penn State's campus.
"He tries to shy away from the attention," Fagnano said. "He doesn't want to be showy or public. That's just not who he is."
But at the charity athlete date auction earlier this month, an auditorium full of students - mostly female - erupted into swoons and applause when Mauti was announced on stage. Mauti's introduction was nearly twice as loud as any other varsity athlete - including 10 of his teammates.
"Oh, we were getting on him for that," Obeng-Agyapong said, laughing. "He's kind of shy about it. He tries to brush it off the best he can."
Mauti was the first player to speak publicly to the media after the sanctions, via a YouTube video he produced alongside teammates. He was also the first player to talk to the team. Defensive end Deion Barnes described that speech as "inspiring."
"The concept of what he was saying was, we are a team,'" Barnes said. "We're still going to be able to be brothers and do the things we want to do."