The 31-year-old was Trinity’s best player during their seven successive defeats at the start of the campaign and has been at the heart of back-to-back wins over Hull KR and Huddersfield Giants which have got their season up and running.
Chester - whose side are at home to Leigh Centurions on Sunday - believes Westerman’s form is more impressive than rivals at clubs higher up the table.
He said: “I might be biased, but I don’t think there’s a lock in the competition who’s playing as good as Joe Westerman is at this moment in time.”
Westerman joined Trinity ahead of last season, having had previous spells with Castleford Tigers, Hull - twice - and Warrington Wolves.
“If you look at the tries we’ve scored in the last couple of weeks, everything’s around Joe Westerman,” Chester said.
“He brings an energy and he has got a bit of freedom on the pitch - he is mixing his game up, he is not just wanting to create, he is doing the tough stuff and I think he’s playing his best rugby in a long time.
“He is such an influential player to us as a team.”
Westerman was substituted early in the second half of last weekend’s game and did not return, but Chester confirmed that was to give him a breather, rather than because of an injury.
“I wanted to rest him up for this week,” he said.
“He has not missed a training session, not missed a game and he regularly plays 80 minutes.
“We have got to keep wrapping our important players like Joe in cotton wool.”
Westerman’s contract ends this autumn and the Evening Post revealed last month he is set to link up again with his former coach Lee Radford at his hometown club Castleford next season.
Chester, though, said nothing has been signed or sealed.
“We’ve had discussions,” he said. “I think Joe wants to see what happens with my position before he makes a decision.
“Whatever happens with Joe, he has given everything for this club for the last two years. If he stays, great - if he moves on, he goes with my and the club’s blessing.”
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