Pundit Michael Stewart insists a "toxic combination" has developed at Celtic and derailed their season.
The Hoops floundered to another bad result in a 1-1 Premiership draw with St Johnstone, extending the current barren run to two wins from 12 games.
That was triggered by a derby day defeat to Rangers back in October and Stewart believes that loss has "decimated" the mentality of Neil Lennon's players.
And he reckons the current team's inability to break down solid defensive units like St Johnstone's, plus growing defensive frailties, has left Celtic fighting a losing battle.
Stewart said on BBC's Sportscene: "I remember before the Rangers game, Neil Lennon spoke about how the result wouldn't determine the league but it would have a psychological effect.
"It really has decimated Celtic. They went into that game on the back of seven victories in a row, after the Ferencvaros defeat.
"And a lot of those results weren't great performances though, you think of Riga away, it was a last minute winner from Elyounoussi. Sarajevo a narrow victory as well, 3-2 at home against Livingston when Livingston could have scored in the last minute.
"Since that Rangers game things it has fallen apart. A lot of the difficulties you could see when they were winning games have just come to the fore.
"They can't break teams down, and they can't defend. It's a toxic combination. It is a toxic combination.
"In the wide areas they don't have players who are confident at committing players one vs one, they don't get overloads in those areas either. It comes too narrow and teams know how to play against that."
