And he fears further results like Saturday’s defeat to Rangers will see change at the top at Celtic Park if performances don’t pick up.
Sutton said “not one player can come out of the weekend with any credit” and believes the dismal show summed up the season so far.
He said: “It wasn’t good – big players were out and the striker situation wasn’t perfect, playing a fourth choice striker, but I’m not blaming Patryk Klimala he’s improved a fair bit – every Celtic player on the pitch peformed poorly.
"After the opening goal they froze and that was completely unacceptable.”
He added: "They’ve scraped through games and the level of performance hasn’t been there. There’s a lack of continuity. I don’t think the system has worked.
“[Neil Lennon] needs to find performances and results from somewhere and the next games will be remarkably tricky.
"The fact that the performances have been so flat and Celtic haven’t clicked so far this season has become a massive problem. There needs to be a drastic change in performance, or else Peter Lawwell might be thinking they need a new voice.”
With Odsonne Edouard out Celtic played Moi Elyounoussi and Patryk Klimala in attack, but a lack of options led Sutton onto Celtic’s Scottish striker.
"It’s good to see him back but he’s killed Neil Lennon in many respects. When the season shutdown for COVID and he let himself go and got out of shape and was left out of the mini-pre-season…. a fit Leigh Griffiths would give Celtic a much better option when Odsonne Edouard is out.
“The fact he can only play a few minutes of games isn’t good enough. He is a player who needs to have a good long hard look at himself - had he conditioned himself and looked after himself better Celtic could be in a far better place.”
But there is hope for his former team-mate, says Sutton who played in Glasgow between 2000 and 2006.
He added: “The season is retrievable for Celtic but they have come up short in the big games. He needs a big performance and maybe he’ll get one against AC Milan on Thursday.
“If this carries on it’s how long Peter Lawwell is prepared to leave it. I played with Neil and love Neil but you can’t defend the performances this season – Saturday wasn’t a one-off.
It was flat. The whole season has been flat and he has to sort it out - he’ll know that.”
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