The Sunday Read: Inside the Art of a Fourth-Line Grinder with Mark Kastelic

BOSTON – Mark Kastelic is meticulous about his pregame routine.

​After the Boston Bruin pours his cup of coffee, out come the goggles. Kastelic straps the protective gear over his eyes and plugs in his red-light therapy panel, placed on the kitchen counter. Music is turned on, and Kastelic stands in front of the glow for five to 10 minutes. Rip, Kastelic’s Golden Retriever, sits at his feet.

“It helps boost your energy and your cells and stuff like that,” Kastelic said. “Our strength [trainers] could probably give you a more in-depth answer.”

Kastelic is right. Red light therapy promotes faster muscle recovery and reduces inflammation for athletes. It is one piece of the puzzle that had Kastelic feeling his best in his second season in Boston.

“Everything is even more natural. Just living in Boston and being in this area for two years now, everything is just comfortable. We have good routines,” Kastelic said. “I felt like right from day one, I fit in with the team, with the city, the culture and everything. As time passes, I just feel like I’m getting more and more comfortable. It really does feel like home now.”

It was the first time in Kastelic’s career that he played all 82 regular-season games with his NHL club. The 27-year-old forward logged 61 games with the Bruins last year after dealing with a concussion and upper-body injury. Kastelic spent the three prior seasons with the Ottawa Senators; he was a fifth-round pick for the organization in 2019.

Kastelic was one of three players – alongside Sean Kuraly and Fraser Minten – to compete in every single Bruins matchup this time around.

“It’s huge. I think the last two years, I’ve gone into the summer with some question marks. I always knew that I would be okay at the end of the day,” Kastelic said. “Coming into this season this year, I was very confident on how I felt, but you never really know until you play a lot of games.”

Night after night, Kastelic further cemented his role in Boston. He was a hard-hitting, hustling stalwart on the fourth line with Kuraly and Tanner Jeannot for the majority of the season, and finished with career-highs in goals (12), assists (10) and points (22). Kastelic logged four points (three goals, one assist) in his last two regular-season contests before making his NHL playoff debut; he had one assist in the six-game stretch.

Kastelic is somewhat built for the postseason. It is a benchmark he and his fiancée, Paige, once only saw from the outside. They both got to experience it for themselves in April.

“I remember we used to watch playoff games on TV, and you could kind of feel the atmosphere through the TV. To be part of it now, it’s very exciting for both of us,” Kastelic said. “You can tell, everything is just more heightened, more physical, more emotions. I think that is just the fun part about it.”

The fourth line stuck together during the playoffs, delivering the same physicality and forecheck that made the trio integral to the B’s success. All three battled on the penalty kill, too.

“They’re two guys who work as hard as they can every night. That’s what we tried to bring to the team – having that identity that’s hard to play against,” Jeannot said. “Playing simple and just bringing energy for the team.”

Jeannot completed his first campaign in Boston after signing a five-year deal in July 2025. Jeannot, who has seven NHL seasons under his belt, turned into a role model for Kastelic, who was finding consistency in his play.

“Having a guy like Tanner come in, he’s been a good mentor for me because he plays a very similar style of game,” Kastelic said. “It just makes me play bigger than I am and play more confident, having a guy like him on the wing.”

The two forwards combined for 18 fights this season – Kastelic with 10 and Jeannot with eight. They picked their spots, giving the Bruins the spark and force of resilience they needed at different points of the game, during different parts of the season. Jeannot led the team with 239 hits. Kastelic was right behind him with 215.

“I think it’s kind of what got me in this league in the first place – just the basics and not doing the prettiest things,” Kastelic said. “Faceoffs, physical, sticking up for my teammates, stuff like that. I think that’s kind of what got me my first opportunity here, and just trying to grow off that.”

They weren't one-trick ponies. Jeannot also finished the regular season with 22 points, marking the second-best total of his career.

“It is exciting to be part of the future here. We got some valuable experience throughout the entire season and then in the playoffs,” Jeannot said. “It’s obviously not how we wanted it to end. It sucks to be done already. But it’s just gaining that experience and using that to move forward.”

Jeannot will have a quieter summer this year, which he is happy about. The 28-year-old was an unrestricted free agent last July, not knowing where he was going to have to pick up and move his family of four.

“It’s definitely kind of a weight off your shoulders, knowing that you’re going to come back and have more of a picture of what lies ahead,” Jeannot said. “Just going to be focused on getting your body in top shape and doing everything that you can to come back and give everything you can for the team again.”

For Kuraly, last year’s free agency landed him in a place that was already home. The 33-year-old forward started his NHL career in Boston (2016 to 2021) before signing with his hometown Columbus Blue Jackets and playing there for four seasons. Kuraly returned to the Bruins on a two-year deal and took on more leadership responsibilities as, suddenly, one of the more veteran guys in the room.

“First of all, it was fun for me personally to be back in Boston. I really enjoyed being back here and being around the guys I was familiar with and friends with before, and also meeting the new guys and integrating into the group,” Kuraly said. “However many years later, you kind of get a buffet of different experiences, and you draw upon them all to see how you can show up as the best version of yourself and help the team navigate the difficulties of an NHL season.”

Like his linemates, Kuraly finished the regular season with 22 points (six goals, 16 assists), and added two points (one goal, one assist) during the playoffs. He anchored the pivot position between Kastelic and Jeannot, delivering a steadfast reliability in this next stage of his career.

“That was a bright spot, I think. They’re simple guys, hockey players, great teammates, great people. They play hard. Just easy people to play hockey with, get along with and be teammates with. I was lucky to have them on my flanks this year,” Kuraly said. “Every year the league and the game just pushes you in a way that you just realize that you’ve still got room to grow and still got things to learn, which is the fun part, but challenging.”

The summer will feel long. It always does. But the fourth line is ready to recharge (red-light therapy included), regroup and get back to its purpose on the ice. It helps that they’re always playing for each other.

“I think the biggest thing is off the ice, they’re just both awesome guys and fun to be around, and makes it easy to play with them when you like them that much as people. Everybody feeds off each other; we built a lot of chemistry throughout the year. We’re always communicating, talking and seeing how we can improve. We know what’s expected of us,” Kastelic said. “I love our group, and I love the way we play. The guys in our room that we have that all stick up for each other and play a hard-nosed style of game.”