JJ Peterka was traded to the Boston Bruins by the Utah Mammoth on Friday.
The Mammoth received the No. 23 pick in the 2026 NHL Draft and a conditional first-round pick in the 2028 NHL Draft. Boston had received the 2028 first-round pick from the Florida Panthers in the deal for forward Brad Marchand on March 7, 2025.
Utah then traded the No. 23 pick to the Detroit Red Wings later Friday for goaltender Sebastian Cossa.
"We've got some really good, younger players coming and I felt like we had to create a little bit of room for them in some areas and some offensive situations," Mammoth general manager Bill Armstrong said. "And I think JJ was a great player for us, obviously, to get two first rounders for him. It's a great value. One first rounder allowed us to go get one of the goaltenders we've been hunting for the last few years, and then I think with the other pick, it allows us to have some ability to make some bigger deals down the stretch with another first rounder in the bank. And so I think it gives us a lot of flexibility. It gives our younger guys an opportunity and gives us an opportunity to put a young kid in net that we feel he's got a chance to really take a step and maybe be a goaltender of the future for us."
Peterka had 47 points (25 goals, 22 assists) in 82 games this season, his first with the Mammoth after being acquired in a trade with the Buffalo Sabres on June 26, 2025. He did not have a point in six Stanley Cup Playoff games.
“Obviously I wasn’t really happy with the way I was playing,” Peterka said on Saturday. “I think I have way more to give than what I showed. I think (I’m) just super excited for the opportunity for me in Boston. I think it’s going to be an awesome fit. Just super excited overall.”
The 24-year-old forward has four seasons remaining on a five-year, $38.5 million contract ($7.7 million average annual value) he signed on the day he was acquired by Utah.
“(Peterka has) speed and skill. He’s got an elite shot," Bruins general manager Don Sweeney said. "He probably gives us another look on the elbow in a power-play situation. His power-play minutes dipped a little bit last year. His 5-on-5 production has been really good. Plays both wings. Could probably play with a couple different types of centers, try to help drive a line, but also complement the better guys in situations that we’re certainly trying to improve, as we said repeatedly. We’ve acknowledged that we’re a competitive group and our guys did a really, really good job last year, but we are trying to get deeper and add speed. Marco (Sturm’s) talked about the forecheck side of things, and adding speed is an element that we felt we needed to continue to address internally with some of the younger players and externally if we could identify them.”
Selected by Buffalo in the second round (No. 34) of the 2020 NHL Draft, Peterka has 197 points (92 goals, 105 assists) in 320 regular-season games for the Sabres and Mammoth.
“In the Buffalo situation, he was asked to drive -- they were a young group -- and he was asked to drive a lot of offense, and he has the ability to do that," Sweeney said. "Utah became a little more complementary because they were pretty top-heavy and had a lot of skill there, they did a really good job to get into the playoffs this year. He lost a little bit of power-play time as a result of that, which he had had in Buffalo. ... It’s adding the ability to score off the rush but also score off the cycle, but have guys that can score in general shooting-wise.”
Cossa went 26-8-4 with a 2.33 goals-against average, .915 save percentage and five shutouts in 39 games for Grand Rapids of the American Hockey League this season.
The 23-year-old, who was selected by Detroit in the first round (No. 15) of the 2021 NHL Draft, can become a restricted free agent on July 1.
"You look at his work in the [AHL] over the last few years, he's at the point where he's accumulated enough games in the [AHL], and his age is absolutely perfect. And now he's going to have that opportunity to take that next step," Armstrong said. "I feel like he was a goaltender that we moved toward, and he has a chance to really step in here and be a huge piece of our club next year."
The Mammoth (43-33-6) qualified for the playoffs in just their second season as a franchise this season. As the first wild card from the Western Conference, they were eliminated by the Vegas Golden Knights in six games in the first round.
The Bruins (45-27-10) finished as the first wild card from the Eastern Conference this season and were eliminated by the Sabres in six games in the first round.
“I’ve seen in the past how important a good relationship with the coach is and if you’re familiar with that kind of stuff,” Peterka said. “So, coming in, having a German coach, having an assistant coach who used to coach me when I was younger is just super exciting overall. So, just super pumped for the opportunity to play in Boston.”
NHL.com senior writer Amalie Benjamin and independent correspondent Matt Komma contributed to this report
