LATROBE, Pa. — Shortly after T.J. Watt moved into his dorm room at Saint Vincent College for his 10th NFL season, the star edge rusher was reminded of one of his first training camps. He recalled former coach Mike Tomlin chatting him up in the hallway, asking about his family and his offseason.“I knew I had a bad rep or two at practice, and he was talking like nothing happened,” Watt said. “I was like, cool, he forgot about it. We go in front of the whole team, and he’s like, ‘Watt, what the hell are you doing?!’”Now, after spending his first nine seasons with one head coach, Tuesday felt like a “first day of school” for Watt, full of uncertainty as the Mike McCarthy era begins in Latrobe. While McCarthy is acutely aware of the Steelers’ history and will fully embrace some aspects, like the 3-4 defense, he’s going to do things his way. For example, Tomlin preferred to practice during the hottest part of the day from 1:30 to 3:30. McCarthy will start his practices at about 11:20 a.m., preferring to do the heavy lifting early and give his coaches plenty of time to dice up the film.Within practice, the pace is quicker. During OTAs, there were no benches for players to rest, like in the past. Around the field, there are significantly more cameras, as the new coach believes in analyzing things in a different way. McCarthy’s specialization on the offensive side of the ball also will lead to changes.“I think the biggest difference for me is it’s an offensive coach,” wide receiver DK Metcalf said. “That’s the first time I’ve had that in my career. So just seeing how you know when the defense messes up, it’s all right next play. But when the offense messes up, we get to go again. I’ve never had that in my career.”DK Metcalf opens up about the Steelers' team bonding tripMike DeFaboPerhaps the most significant change will be the amount of physicality in camp. Tomlin often said that “you can’t box without sparring.” Two years ago, The Athletic conducted an informal poll, which led to the conclusion that the former coach conducted, arguably, the NFL’s most physical camp.McCarthy will choose to do things more methodically and carefully. There will be no live tackling during team periods. Instead, he’ll use dummies and other methods that emphasize footwork to instill the fundamentals; it won’t require Steelers-on-Steelers combat in the same way.