"You think about it, a year ago he's playing public high school hockey (at Eden Prairie High in Minnesota) and now he's got a year of college hockey under his belt and a couple NHL games," assistant general manager Steve Greeley said. "I think when we got him here in the spring, it opened his eyes up a little bit to what it means to be a National Hockey League player, what the guys are doing after a game in terms of workouts and how they're eating.
"I think the Casey we're seeing now is more mature, more refined in terms of trying to become an everyday great National Hockey League player. To me, it's natural."
Mittelstadt (6-foot-1, 201 pounds) signed with the Sabres after completing his freshman season at the University of Minnesota, where he had 30 points (11 goals, 19 assists) in 34 games. He also helped the United States to a bronze medal at the 2018 IIHF World Junior Championship, with 11 points (four goals, seven assists), and was named most valuable player of the tournament.
His busy year was supposed to include a trip to the IIHF World Championship in Denmark in May. Although Mittelstadt was unable to participate because of a groin injury, he showed no signs of the injury during development camp.
"I had to take a break and I couldn't really train, couldn't skate so I was bouncing off the walls for a few weeks and then I definitely missed [the World Championship]," Mittelstadt said. "It's always tough, it's something I've always watched; watched the college kids do that, at least the ones who played college the year before. That was definitely tough, but I felt good [in development camp], which is a sign of improvement."
Mittelstadt won't be the only young player with big expectations for the Sabres this season. Rasmus Dahlin, an 18-year-old defenseman and the No. 1 pick in the 2018 NHL Draft, is expected to play in the NHL immediately.
"It's awesome, I think he really floats around out there and it doesn't even look like he's trying at all, and he's gliding by guys," Mittelstadt said of Dahlin. "It's pretty cool. You can see how good of a skater he is and how good his hands are. ... It's definitely really exciting and it's a big piece for us."