Dahlin already has a fan in Mittelstadt.
"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. "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."
Mittelstadt, 19, had five points (one goal, four assists) in six games with the Sabres after he signed his entry-level contract March 26. He could slot into the No. 2 center spot in place of Ryan O'Reilly, who was traded to the St. Louis Blues on July 1.
Buffalo acquired Sheary in a trade from the Pittsburgh Penguins on June 27 and got Berglund and Sobotka as part of the O'Reilly trade. The Sabres added more scoring when they traded a prospect and draft picks to Carolina for Skinner, who scored at least 20 goals in six of his eight seasons with Carolina, including an NHL career-high 37 in 2016-17, and won the Calder Trophy as NHL rookie of the year in 2010-11.
"You look at even-strength scoring the past couple of years in Buffalo," Botterill said. "One of his strengths, he's a consistent goal-scorer. We had to create more offense."