On Saturday night in Boston, Mark Kastelic made it clear: he’s not the kind of player you want to square up with unless you’re ready for a real battle. The former Ottawa Senator, now wearing black and gold for the Bruins, found himself in the middle of a heated scrap with Detroit Red Wings defenseman Moritz Seider - and it didn’t take long for things to get physical.
The altercation came late in the first period, sparked by a heavy collision in the corner. Kastelic and Seider exchanged words, then shoves, and before long, gloves were off. What followed was a mismatch in experience and fighting pedigree, and the results showed.
For Seider, this was only his second NHL fight - a big leap from his first, which came two years ago against Nashville’s Filip Forsberg, a skilled forward but not exactly known for his fists. Kastelic, on the other hand, is a seasoned enforcer.
He’s logged 38 professional fights, and at 6-foot-4 and 234 pounds, he brings real heavyweight credentials to the ice. Seider, while no slouch at 6-foot-2 and 210 pounds, was clearly outgunned.
Once the punches started flying, Kastelic wasted no time asserting control. He connected with several hard right hands, backing Seider up and leaving the Red Wings blueliner with little room to respond.
It was a one-sided affair, and one that raised eyebrows - not just because of the result, but because Seider was allowed to engage without any interference from his teammates. In a league where protecting your stars is often priority number one, that kind of freedom in a fight is rare.
Kastelic’s name might still ring a bell for Senators fans. Drafted 125th overall by Ottawa in 2019, he spent four years in the organization, including two in the NHL. He was part of the trade that sent Linus Ullmark to the Senators two summers ago - a deal that, at the time, raised some eyebrows but has since settled into the background of both teams’ roster moves.
There’s also a bit of off-ice connection here: Seider is a close friend and summer training partner of Tim Stützle, the Senators’ star forward. So while this fight didn’t have the makings of a rivalry bout on paper, there’s some shared history between the players involved - and that always adds a little extra spice.
For the Bruins, Kastelic’s presence brings a physical edge that fits right into their identity. He’s not just a fighter - he’s a tone-setter, the kind of guy who can shift momentum with his fists as much as his forecheck. And on Saturday night, he reminded everyone that in the trenches, few are tougher.
As for Seider, this might be one of those learning moments. He’s already established himself as one of the league’s top young defensemen, but toughness in the NHL comes in many forms.
Dropping the gloves against a veteran brawler like Kastelic? That’s a whole different challenge - and one he now has firsthand experience with.