A fringe first-grader last year, Cartwright has played himself back into the big league in his third season with the Eels, who have been forced to reconfigure their forward pack after injuries and off-season departures.
The one-time State of Origin hopeful has averaged more run metres than in any season since 2016 and added an offload into his game to provide the Eels with go-forward during their underwhelming 4-7 start to the year.
After being criticised for his effort in defence earlier in his career, the former Panther and Titan is averaging 26 tackles per game.
"Bryce has been huge," Gutherson said.
"We've really simplified what he needs to do for the team, and I think he's bought into how we'd like him to play.
"It takes time when you come to a new team and you're not playing the style of footy that the coaching staff and the team want you to play.
"It takes time to earn that trust, and I think this year he's really earned the trust with the footy that he's been playing."
Cartwright is set for the biggest challenge of his season yet - replacing the influential Shaun Lane on the left edge for up to two months.
A hamstring injury forced Lane out of the round-11 loss to Canberra and, having lost him to a jaw fracture for the first five weeks of the season, the Eels are preparing to do without their reigning player of the year for between six and eight more weeks.
The injury has led coach Brad Arthur to promote Cartwright to the starting side, where the 28-year-old will work with Dylan Brown to spark the left edge that tore rivals open in 2022.
"(Cartwright) is playing tough and he's doing all the little things that people may not see watching the game, but you know that he's doing it on the field when you're playing with him," Gutherson said.
"He's probably in career-best form, and we need him to go to another level now that Laney is out."
The Eels need Cartwright at his best, given they sit in 14th place and face ladder-leading South Sydney on Friday night, but are remaining calm amid a two-game losing streak.
"If you win two or three on the trot, everyone forgets about it - you're sitting comfortably again," Gutherson said.
