The JJ Peterka experiment lasted almost exactly one year in Utah.

After being traded from Buffalo to Utah on June 25, 2025, the 24-year-old German winger found himself on the move again on Friday, this time joining German head coach Marco Sturm in Boston.

The Mammoth received the 23rd pick in Friday’s NHL draft from the Bruins, along with a 2028 first-round pick, in return, but that 23rd overall selection did not stay in Utah’s hands for long.

After trading up to draft 6-foot-5 winger and Michigan State commit Ethan Belchetz at No. 17, the Mammoth sent No. 23 to Detroit for goaltender Sebastian Cossa.

“JJ was a great player for us and to get two first-rounders for him is a great value,” Utah General Manager Bill Armstrong said. “One first-rounder allowed us to go get one of the goaltenders we’ve been hunting for the last few years.”

You read that right. Armstrong has had his eye on the 23-year-old goalie since at least the 2021 draft, when Cossa and fellow Edmonton Oil King Dylan Guenther (you might have heard of him) were both selected in the top 15.

Goalie of the future?

The timeline for NHL goaltenders is uniquely long, not unlike that of an MLB pitcher.

“It’s a tough position when you’re drafting somebody and say, ‘Hey, well, we’re gonna see you six or seven years down the road,’” Armstrong said. “You’ve got to be patient with them, and I feel like he was a goaltender that we moved towards and he has a chance to really step in here and be a huge piece of our club next year.”

Cossa spent the last three seasons playing for the Red Wings’ AHL affiliate, the Grand Rapids Griffins, but did make a single appearance for Detroit in December 2024 to technically earn his NHL debut.

Armstrong believes Cossa is ready to be a full-time backup in the NHL now, and he will likely get that opportunity next season for the Mammoth as last year’s backup, Vitek Vanecek, hits free agency next week.

In an ideal situation, the starter and backup split regular-season starts evenly, but Karel Vejmelka started 64 of Utah’s 82 games last season, while Vanecek played in just 22 games and won five.

Cossa played in 39 of Grand Rapids’ 72 games last season, finishing with the third-most wins among AHL goalies and top six in both goals-against average and save percentage.

“He’s at the point where he’s accumulated enough games in the American Hockey League, and his age is absolutely perfect,” Armstrong said. “Now he’s going to have that opportunity to take that next step.”

Creating room on offense

Speaking of young players taking the next step, the up-and-coming forwards in Utah’s pipeline are what ultimately led Armstrong to pull the trigger on a Peterka trade in the first place.

Tij Iginla, Cole Beaudoin and Caleb Desnoyers are Utah’s three first-round draft picks yet to make their NHL debuts, and all three spent time at or near the top of the scoring leaderboard in their respective CHL leagues last season.

Iginla — the first draft pick in Utah NHL history at No. 6 in 2024 — led the bunch with 90 points for the Kelowna Rockets, good for the sixth-most in the WHL on the year. He also happens to play on the wing, like Peterka.

“We’ve got some really good younger players coming,” Armstrong said. “And I felt like we had to create a little bit of room for them in some areas and some offensive situations.”

Armstrong included 2025 NHL debutant Daniil But, 2024 fourth-round pick Gabe Smith and the recently drafted Belchetz, along with the aforementioned first-rounders, as the forwards he sees pushing for NHL minutes in the near future.

He also left the door open for some more moves to be made “down the stretch,” with rounds two through seven of the NHL draft on Saturday and free agency beginning on July 1.

“It gives us a lot of flexibility,” Armstrong said of the Peterka trade. “It gives our younger guys an opportunity; it gives us an opportunity to put a young kid in net that we feel has got a chance to really take a step and maybe be a goaltender of the future for us. You never know.”