Hoffman needed extensive repairs after Newcastle's 1-all draw with Wellington in round 18 and spent the last three months of the season in rehabilitation-and-recovery mode.

But the 30-year-old has been working hard while his teammates enjoyed their off-season break and hit the ground running when training resumed this week.

"He's fully over the injury, 100 per cent," Merrick said.

"There's no pain whatsoever.

"He's running really hard and he's back to normal.

"It's like he didn't have an injury at all. The operation went well and there's been no after-effects.

"He's had a really good off-season and had a very heavy running program, so he's in good shape."

The only player to have appeared in both of Newcastle's grand finals, Hoffman is one of Merrick's senior statesmen, with 200 games to his name. His ability to play as a defender or in the forward line is as valuable as his experience.

Merrick had no complaints about the physical state of his troops when they clocked on this week for their first day of pre-season.

"The squad's looking very fit," he said.

"The boys have come back very lean. Kaine Sheppard has lost four kilograms.

"Steve Ugarkovic is slimmer than ever. Nobody has put on any weight. It's very impressive. I think they're all very determined after what was a difficult season."

Merrick said new signing Nick Fitzgerald had been quick to make an impression.

"Nick has posted the highest fitness numbers at training so far, so he's setting a high standard," Merrick said.

Meanwhile, former Jets midfielder Riley McGree has signed a three-year deal with his original club, Adelaide.

McGree will return from Club Brugge, where he didn't play a senior game. He spent last A-League season with Melbourne City. "Adelaide had a very good season last year and were unlucky to miss out on a place in the grand final, so I have big ambitions for the club and myself," McGree said.