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Utah Mammoth goaltender Karel Vejmelka defends the goal against the Anaheim Ducks (Gary A. Vasquez-Imagn Images)

Breaking Down the Utah Mammoth’s Opening Night Roster

Originally posted on The Hockey Writers
By Chase Beardsley | Last updated Oct 7, 2025 3:50 PM ET

The Utah Mammoth’s season opener is just a couple of days away. We now know who will be on the team on opening night on Thursday, thanks to the NHL’s deadline of roster submissions passing on Monday.

That said, there are still some questions left about who will play in Denver against the Colorado Avalanche. Here is a complete breakdown of the Mammoth’s opening-night roster, along with my best shot at projecting the team’s lines.

The Forwards:

Nick Schmaltz, Clayton Keller, Dylan Guenther, Brandon Tanev, Jack McBain, Barrett Hayton, Andrew Agozzino, Michael Carcone, Kailer Yamamoto, Lawson Crouse, JJ Peterka, Kevin Stenlund, Logan Cooley, Alex Kerfoot (Long-term injured reserve, LTIR)

Not a lot of surprises among the forward group. It’s mostly the same team from last season returning, along with the offseason additions of Peterka and Tanev. It’s good to see Yamamoto make the roster after a fantastic 2024-25 season with the American Hockey League’s (AHL) Tucson Roadrunners and a couple of impactful appearances with the Mammoth.

Kerfoot will start the season on LTIR after sustaining a lower-body injury during training camp. It’s unclear how long it’ll be before he returns. Liam O’Brien will also start the season injured, but notably on the injured non-roster list instead. With the team continuously improving, O’Brien has been pushed out of the roster. It would be surprising if he spends the whole season in the AHL or in the press box, assuming he’s not injured, but it does show that the Mammoth will be icing the best roster possible, no matter who is subbed out.

There were two surprises on Tuesday. The first was Agozzino making the roster. Assuming he plays on Thursday, it’ll be the first time he suits up for an NHL game since the 2022-23 season with the San Jose Sharks. It’s well deserved considering his strong 43-point 2024-25 season with the Roadrunners and his even stronger training camp. We’ll see how long he stays up in the NHL, but making the roster straight out of camp should be an achievement that the player and team should celebrate.

The second surprise was the late signing of free agent Rooney, who attended the New Jersey Devils’ training camp on a professional tryout agreement (PTO). It’s a one-year, two-way contract, which helps the Mammoth’s depth a lot. He was sent down to the AHL on Tuesday, but he is an option.

It wouldn’t be surprising if the Mammoth made this signing in response to Curtis Douglas being claimed off waivers by the Tampa Bay Lightning on Monday. The Roadrunners are losing a lot of grit with the departure of Douglas. Rooney will help make that up thanks to his gritty and physical play.

Notable exclusions from the roster include Daniil But, Tij Iginla, and Cameron Hebig. But and Hebig were sent down to the AHL while Iginla was sent to the Western Hockey League. I’d imagine But doesn’t play the whole season with the Roadrunners; rather, he takes the time to adjust to the way the sport is played in North America and is eventually called up.

If the Mammoth suffer injury issues, it wouldn’t be crazy to see Hebig called up. After a career campaign with the Roadrunners and an extended training camp look, it’s arguable that, along with Agozzino (if he gets sent down), Hebig is the best depth option the team has in the AHL.

The Defense:

Olli Määttä, John Marino, Dmitri Simashev, Ian Cole, Sean Durzi, Nick DeSimone, Nate Schmidt, Mikhail Sergachev

Again, not a lot of surprises here. All six of the returning defensemen from last season are on the roster, plus Schmidt, who was signed over the offseason.

Juuso Välimäki will begin the season on the Mammoth’s injured non-roster list as expected. When healthy, Välimäki will more than likely return to the Roadrunners as he tries to make a return to the NHL after an abysmal 2024-25 season.

Congratulations to Dmitri Simashev for making the NHL roster straight out of his first NHL training camp. The biggest surprise among the eight defensemen, Simashev had a decent camp. I am a bit surprised that he wasn’t assigned to the AHL to continue to improve his game and play top minutes, but general manager Bill Armstrong made it clear that he doesn’t see either him or But playing much down there.

The Simashev addition does throw a wrench into things. How is the lineup going to work? All six returning defensemen, plus Schmidt, absolutely deserve to be in the NHL. However, the Mammoth wouldn’t keep Simashev in the NHL just to be a healthy scratch. Will the Mammoth role with seven defensemen and keep DeSimone as an extra? It’s an interesting problem they’ve created here.

The Goalies:

Vítek Vaněček, Karel Vejmelka

No surprises at all here. Once Connor Ingram and the Mammoth agreed to part ways, it was clear who the two NHL goaltenders would be. However, the role of starter might be more contested than some might think.

Vaněček had a really strong preseason, while Vejmelka at times didn’t look his best. It’s just preseason, so it doesn’t matter much, but it could be something to watch out for. We know how good goaltending coach Corey Schwab is at turning around goalies’ careers. As of right now, though, all signs point to Vejmelka as the starter against the Avalanche on Thursday.

Projected Lines:

Last season, the Mammoth finished out their season on the road against the St. Louis Blues. These were their lines.

Keller-Cooley-Guenther
Schmaltz-Hayton-Yamamoto
Crouse-McBain-Doan
Kerfoot-Stenlund-Bjugstad

Sergachev-Durzi
Cole-Kesselring
Määttä-Bortuzzo

Vejmelka
Villalta

Obviously, there are a couple of players who are no longer on the team, including Josh Doan, Nick Bjugstad, Michael Kesselring, and Robert Bortuzzo. Matt Villalta was assigned to the Roadrunners during camp. Marino was injured during the final couple of games of the season.

That provides us with two open spots in the forward group, two spots on the blue line, and the backup goalie role.

Starting with the forward group, one of those spots will go to Tanev, whom the Mammoth signed in the offseason. Another will go to Peterka, who will be in the top six right off the bat after being acquired from the Buffalo Sabres.

You also have to remember the Kerfoot injury. While he’ll slot back into the lineup when he returns, it does provide an opportunity for someone to step in and try to win a permanent spot in the lineup. That means that the final spot will go to either Carcone or Agozzino.

Agozzino’s camp was really good, but does that push him over Carcone? I don’t think so. Carcone is a great depth option who flexed his elite forechecking in every preseason game he appeared in.

For now, Carcone will probably get the spot in the lineup, but it wouldn’t be surprising if he, Agozzino, and Yamamoto rotate in and out of the lineup before Kerfoot returns. With that, here is my prediction of the opening night forward lines.

Keller-Hayton-Schmaltz
Guenther-Cooley-Peterka
Crouse-McBain-Yamamoto
Carcone-Stenlund-Tanev

Extra: Agozzino

With the addition of Peterka and his chemistry with Guenther in the preseason, the Mammoth will probably try to make a line of those two with Cooley, especially due to the success Cooley and Guenther have had together in the past. The Keller, Hayton, and Schmaltz line has been elite in the past, and putting them together for another season might pay off dividends.

However, don’t be surprised if the top six are jumbled up. We’ve seen combos like Keller and Cooley together pop off. Also, don’t take the first and second line labels too seriously. My guess is we’ll see these two lines get deployed equally.

The bottom six is pretty much what you’d expect. Yamamoto on the third line over Tanev is because Yamamoto thrives with more minutes, while you can give Tanev bottom-line minutes, and he can still flourish. Otherwise, nothing really surprising.

The defense is pretty easy to predict other than where Simashev fits into the lineup. It’s going to be really intriguing to see how the Mammoth figure that out. I could see a scenario where they roll with seven defensemen and scratch someone like Carcone or Yamamoto, but there’s a reason why NHL teams don’t do that consistently.

I also wouldn’t be surprised if Simashev is eventually sent down to the AHL to get top minutes down there rather than get minimal or no ice time in the NHL. Genuinely, the defense might be the hardest thing to predict for the Mammoth. Here’s my prediction for opening night’s pairings.

Sergachev-Durzi
Määttä-Marino
Cole-Schmidt

Extras: Simashev, DeSimone

We’ll eventually get to the point where Simashev is in the lineup over someone like Cole. Maybe it’ll even happen Thursday night. However, as of right now, Cole should be on the blue line over Simashev. Of course, head coach André Tourigny could switch it up and go seven defensemen. Only time will tell.

Mar 24, 2025; Salt Lake City, Utah, USA; Utah Hockey Club defenseman Ian Cole take a shot against the Detroit Red Wings during the first period at Delta Center. Mandatory Credit: Rob Gray-Imagn Images

Goaltending is pretty easy to guess with Ingram being traded to the Edmonton Oilers. It’ll be intriguing to see if Vaněček can catch up to Vejmelka, but as of right now, it’s Vejmelka’s net.

This is a much better lineup than last season, even if you remove the injury to Marino. Outside of potentially Hayton, the Mammoth’s top six is filled with elite players. The team’s top four on the blue line stacks up to the best in the Western Conference, and Vejmelka showed he can be a great goaltender with his play last season.

It’ll be a tough battle on Thursday against the Avalanche, who will once again be deploying a stacked roster. However, the teams split the season series last season. Perhaps this new-and-improved Mammoth team will present the Avalanche with an even tougher challenge than last season. Come Thursday night, we will know, but for now, the Mammoth have done exactly what they needed to do on paper after missing the playoffs last season: become a deeper and better team.