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Seamus Casey, New Jersey Devils (Jess Starr/The Hockey Writers)

Inside the Devils’ Defensive Dilemma with Nemec and Casey

Originally posted on The Hockey Writers
By Donnah Campbell | Last updated Aug 3, 2025 10:25 AM ET

At the start of the offseason, the New Jersey Devils were in a unique position, with a surplus of defensive talent on their hands. Last month, they parted ways with Brian Dumoulin, who signed a three-year deal with the Los Angeles Kings. While this might have temporarily eased their logjam of left-handed defensemen, an issue still remains in terms of right-handed blueliners.

With Johnathan Kovacevic out for an indefinite amount of time, missing the start of the regular season with a knee injury, someone will have to fill in as Jonas Siegenthaler’s partner. Which leaves Simon Nemec and Seamus Casey, who remain the Devils’ best up-and-coming defensemen. For a while, it appeared that the Devils would utilize either player as a bargaining chip in a larger trade, but now it seems an unlikely scenario. Meaning, both young defensemen will fight for a spot on the roster during training camp.

Can Simon Nemec’s Success Continue?

The Devils drafted Simon Nemec second overall in 2022, and he has certainly shown potential as a future top defenseman. He has spent a significant amount of time in the American Hockey League (AHL) with the Utica Comets, with 19 goals and 46 assists throughout three seasons. However, his NHL performance has been filled with inconsistencies.

During his rookie season, he earned 19 points across 60 games and averaged 19:52 in ice time. He was especially effective in 5-on-5 scenarios. He recorded a 52.28 expected goals percentage (xGF%), and Devils goaltenders had a .908 save percentage (SV%) with Nemec on the ice. Unfortunately, his second season in the NHL was filled with struggles, and Nemec posted just four points in 27 regular-season games.

But in spite of his sophomore slump, he managed to redeem himself during the 2025 Stanley Cup Playoffs. He was the hero of Game 3, scoring the game-winning goal in double overtime. Not to mention, he was also named to Slovakia’s preliminary Olympic roster and will represent his home country in 2026. However, Nemec is entering the final year of his entry-level contract, and the upcoming season will be a pivotal moment in his career. Can his exceptional playoff performance carry over into 2025-26, or will he be unable to rise to the challenge?

Will Seamus Casey Have a Breakout Season?

Casey played just 14 regular-season games in 2024-25, but his small sample size looked incredibly promising. He made quite the splash during the Global Series, since his first career NHL goal propelled the Devils to a 3-1 win, as they swept the Buffalo Sabres in Prague.

His offensive flair continued, with a 33.3 shooting percentage and a plus-3 rating throughout last season. According to MoneyPuck, he averaged 2.71 points per 60 minutes, and finished the 2024-25 regular season with four goals and four assists. One aspect of his game that made an immediate difference was his power-play contributions. Casey’s on-ice stats included a 72.73 shots for percentage (SF%), an 80.55 xGF%, and a 100% high-danger goals for percentage (HDGF%).

He also had a phenomenal rookie season in the AHL, despite being sidelined with a wrist injury for two months. In 30 games with the Comets, he tallied three goals and 15 assists. In fact, he was named to the AHL 2025 All-Star Classic Roster before his injury forced Nemec to take his place. Nonetheless, since Casey utilized his time in the minor league to refine his defensive talent, there is a high likelihood that 2025-26 could be his breakout season.

Who Has Better On-Ice Chemistry?

Aside from their individual contributions, it’s important to look at how well Nemec and Casey mesh with their linemates. Nemec spent the most time skating alongside Brenden Dillon, while Casey’s primary partner was Nemec, skating on his left in order to fill roster gaps. In 5-on-5 situations, Nemec caused Dillon’s goals for percentage (GF%) to decline 14.95%, while also making his HDGF% decrease 44.44%. Aside from these indicators, the Dillon-Nemec pairing was fairly successful, on the ice for 64 scoring chances and 65 shots on goal.

The Casey-Nemec pairing was largely unsuccessful, with very limited on-ice chemistry. Together, they had a 35% Corsi, along with a 28% high-danger scoring chances percentage (HDCF%). Since both players are rather offensive-minded, they need a reliable, defense-driven partner, like Siegenthaler.

Ironically enough, both Casey and Nemec spent time paired with Siegenthaler last season, and the stats highlight Casey’s offensive prowess. The Siegenthaler-Casey defense unit boasted a 76.92% Fenwick (FF%) and 90.97 xGF%, as compared to Siegenthaler-Nemec’s 32.26 FF% and 34.98 xGF%. The Devils already have a tried and true offensive defenseman in the form of Dougie Hamilton, but Casey could provide additional scoring in tandem with Siegenthaler’s shutdown mindset. Overall, both young defensemen could benefit from being paired with a seasoned veteran, but only time will tell who comes out on top.

Nemec and Casey Moving Forward

It will be interesting to see what unfolds at training camp, as the two up-and-coming defensemen compete for Kovacevic’s spot. Both are on the hunt for increased ice time, each trying to prove that they are ready to be a full-time defenseman at the NHL level. Nemec is fighting to stay on the team after not playing to his full potential, while Casey remains an underdog rookie on the verge of a breakout performance.