Not including rookies or players who missed significant time in 2023-24 or 2024-25, I wanted to list the skaters who have improved and declined the most from their 2023-24 campaigns.
I'm going to be relying a little on my player-game ratings as it gives me a simple number to compare against.
An average player rating for forwards is 6.41 and 6.39 for defenders. This is averaged out over 870 skaters who have played in 2024-25.
Anaheim Ducks
Biggest Improvement: Jackson LaCombe

LaCombe has seen himself go from a sixth or seventh defender on the Ducks to a top-two defender in less than six months. He has improved his production from 0.24 points per game to 0.58 and he has maintained his 50/129 hits/blocks in 71 games to 56/106 in 62 games. He has played 42.8% of the time on the power play and 43.6% on the penalty kill. His ice time has gone from 19:23 to 21:45. He has surged ahead of Pavel Mintyukov and Olen Zellweger on the depth chart for now.
Biggest decline: Jacob Trouba

Over the past four seasons, Trouba's points per game have gone from 0.48 to 0.37, to 0.32 and 0.19 in 2024-25. His hit/block peripherals are still strong at 147/187 but he had 191/184 in 69 games in 2023-24, so his physicality is going down a little. His ice time has gone from 22:26 in 2021-22 to 20:36 in 2024-25. Trouba has become a below-average defender in Anaheim.
Calgary Flames
Biggest Improvement: Matt Coronato

Coronato has hit 20 goals in his second NHL season. He has averaged 50.3% of the time on the power play and increased his ice time to 17:22. He had a frustrating 2023-24 split between the NHL and the AHL but probably just wasn't ready for the NHL. At this point, he's a solid top-six NHL player.
Biggest Decline: Yegor Sharangovich

Sharangovich has had up and down NHL campaigns since 2021-22, so I wouldn't be shocked if his 2025-26 season he gets back to 25-30 goals. Unfortunately for fantasy owners, if Sharangovich is not producing, he's not worth having in any multi-category pools.
Chicago Blackhawks
Biggest Improvement: Ryan Donato

Donato had prior career-highs of 16 goals, 18 assists and 31 points in his previous seven NHL seasons. In 2024-25 he exploded for 25 goals, 28 assists and 53 points in 69 games. He has also exceeded 100 hits for the second time in his career and set a career-high with 200 face-off wins (FOW) so far after never having more than 98 before.
Biggest Decline: Philipp Kurashev

Kurashev's 2023-24 season was obviously an aberration as he averaged 0.72 points per game and played over 19 minutes per game. He also had six power-play goals (PPG) and 19 power-play points (PPP). In his 235 other NHL games, including 2024-25, Kurashev has put up just 74 points which is 0.31 points per game.
Colorado Avalanche
Biggest Improvement: Martin Necas

Necas did have 71 points in 82 games in 2022-23 but followed that up with 53 points in 77 games in 2023-24 with Carolina. He took an even bigger step in 2024-25 with 75 points in 71 games split between Carolina and his new team, Colorado. He's playing 74% of the time on the power-play in 2024-25 which is higher than his previous career-high of 59.4 in 2022-23. It has translated to 32 PPP in 71 games this year compared to 26 in 2022-23.
Biggest Decline: Charlie Coyle

Coyle peaked in 2023-24 with Boston where he had 25 goals and 35 assists (0.73 pts/g) in 82 games. He also had 131 hits and 762 FOW while averaging just over 18 minutes per night. In the two seasons prior, he had averaged between 0.54 and 0.55 points per game and won over 535 faceoffs in both campaigns. Everything has fallen off in both Boston and Colorado in 2024-25. He has just 0.33 points/g and even though he has played 72 games, he has just 99 hits and 307 FOW.
Dallas Stars
Biggest Improvement: Evgenii Dadonov

Dadonov is 36 years old now and it looked like after his 20 goals and 43 points (0.55/g) in 78 games with Vegas in 2021-22 he was going to decline from that point on. His next two seasons with Montreal and Dallas were 33 points in 70 games (0.45/g) and 23 points in 51 games (0.45/g). He rebounded in 2024-25 with 16 goals and 20 assists in 67 games with Dallas and could reach 20 goals again. He's had a good year.
Biggest Decline: Mikko Rantanen

Rantanen's struggles since leaving Colorado have been well-documented, but it's a little surprising that it has continued from Carolina to Dallas at about the same level. In Colorado, he was one of the most consistent producers over the past four or five seasons, with or without Nathan MacKinnon in the lineup. Between 2020-21 and 2023-24, his points per game were between 1.23 and 1.3 and he didn't have one quarter under a point-per-game during that period. His FOW have gone from 275 in 80 games to 129 in 69 games.
Edmonton Oilers
Biggest Improvement: Jake Walman

Walman has only played eight games with the Oilers, but he's playing at a similar level to what he was with San Jose all year. He has gone from an average defender to an above-average top-four defender in the space of a year. He has put up 29 ES points in 58 games (0.5/g) after a career-high of 21 points during his whole career. He has set a career-high in hits (54) and has blocked 134 shots. His ice time went from 19:46 to 23 minutes.
Biggest Decline: Viktor Arvidsson

The good news for the Oilers is that Arvidsson has managed to play 55 games in 2024-25. The bad news is that they probably expected the player who averaged over three SOG per game and scored 20 goals or more five times in his career. He's still a very steady player, who could contribute in the playoffs, but his play has dropped off from what he had been.
Los Angeles Kings
Biggest Improvement: Alex Laferriere

Laferriere was a very effective third or fourth-line player as a rookie in 2023-24 who posted 12 goals and 11 assists in 81 games while putting up 113 hits. He elevated his play in 2024-25 to a top-six player who might get to 20 goals and 20 assists, with 100 hits.
Biggest Decline: Trevor Moore

Moore had an outlier season in 2023-24 with 31 goals and 26 assists (0.7/g) in 82 games while posting 92 hits. He never had more than 17 goals, 49 points or 69 hits before that. He is still a very effective second or third-line player in 2024-25 but his production has come down to 0.54/g in 59 games and he won't reach 20/20 goals or assists.
Minnesota Wild
Biggest Improvement: Marco Rossi

Rossi had an impressive 2023-24 with 21 goals and 19 assists (0.49/g) in 82 games to go along with 335 FOW. He built on that in 2024-25 with 22 goals and 32 assists (0.77/g) in 70 games and increased his FOW to 404.
Biggest Decline: Gustav Nyquist

I think we all knew that Nyquist wasn't going to be able to duplicate his 75 points in 81 games (0.93/g) that he had with Nashville in 2023-24. I don't think we realized how far his production would fall. He has produced just nine goals and 14 assists (0.34/g) and for a player who doesn't hit, block shots or take faceoffs, his value takes a nosedive in most multi-category pools.
Next week, we will focus on the rest of the Western Conference Teams.
Thank you very much for reading and if you have any comments, please leave them below or follow me on Twitter @gampbler15