As he took a slow walk up the Celtic tunnel on full-time, it wasn't hard to feel something for Wilfried Nancy, a haunted manager on the end of a sixth defeat in his eight games. Over-promoted and out of his depth.

A first half at Celtic Park that offered such promise made way for another second half of dismal collapse. They had Rangers on the ropes at the break but you always sensed that they needed a second goal to put them on the floor and maybe a third just to put them out for the count. These are Celtic's frailties these days. One goal is never enough. Those goals never came despite the chances they had.

Once Rangers started to fight back, they hit Celtic with three blows in 21 minutes. Ruthless. The Celtic lights went out in an instant. From light to dark in the blink of an eye. The colossal weaknesses in Nancy's formation, the giant amounts of space conceded by his players were the problem again. That and their inability to stay in the fight.

Was their feeble demise a window to their collective soul, a reflection of their spirit under the new, and surely doomed, manager? It looked like that. A lost dressing room? Perhaps. Just because it's a cliche doesn't mean it isn't true. Once Rangers made it 2-1, Celtic had nothing left, only more indecision, more doubt and more tactical switches that defied logic.

Their new signing, Julian Araujo, is a right-back, when he plays, which is not often. He's had one game this season for Bournemouth and got sent off in the last minute. In the derby, he came on at right wing-back, a move that meant that the dangerous Yang Hyun-jun had to be moved from the right to the left. Why do that? It was like a gift to Rangers. Araujo was then deployed at right centre-half. He was on the field for 23 minutes and played two positions that he's not familiar with. In an Old Firm debut. On his debut. With his team already 2-1 down and the crowd growing angrier by the second. He worked hard, but he must have been wondering what madness had descended on him.

Rangers were far from great, but they were dogged and they hung in there and when their chances came they buried them. Youssef Chermiti, of all people, was the chief tormentor. In nine pulsating minutes he doubled his total for the season and wrote his name into a new kind of Rangers pantheon - from zero to hero.

Nancy spoke later and in trying to talk his way through the latest submission from his team he only reaffirmed his sense of distance from footballing reality. He mentioned that Celtic "deserved more" than a 3-1 loss, when they didn't. Not taking their chances when they had them was on Celtic, not anybody else. Deserve had nothing to do with it.

It was the Celtic board who created a situation where their manager was left with scant options upfront. From meagre rations, he plumped for Johnny Kenny. It didn't work out. The Frenchman made some comments about the loss not being about players and tactics. "It's about moments, it's about details," he said, as if moments and details exist in a parallel universe from players and managers. "It's not about myself," he said. Well, it is, but to a point. It's also about the players he has confused and bewildered with his ill-fitting shape and the ideology he refuses to alter no matter how befuddled things become.

On Friday, he made much of how difficult it's been to introduce his system without a pre-season to bed-in his ideas. He didn't have a pre-season to work with his players and he didn't have a transfer window to bring in more players that could play his system. And yet he pressed on with the system regardless. Stubbornness? Arrogance? Naivety? All three at once?

Danny Rohl went into Rangers, surveyed what he had and got pragmatic. Like Nancy, he needs new players, too. Many of them. But he's found a way to drag his team forward when his counterpart has only succeeded in taking his players backwards in the pursuit of something that only he can see.

The soft progress achieved under Martin O'Neill has been sacrificed on the altar of "process" and some self-regarding notion that Nancy is a visionary who's building a footballing monument. This Celtic malaise is not just about the manager, though. It's about the man who put him forward for the position, Paul Tisdale, the club's director of football operations. What was the process? Who else was spoken to? How much due diligence was done? Was this a thought-out strategy or a punt? Given everything we have seen, the only case to be made is for the latter. There isn't a shred of evidence that Nancy was the right man for this pressure-filled job. Not then and not now.

We can carry on here. Nancy, Tisdale - and, of course, the Celtic board who ratified the appointment. The toxicity between board and supporters is now touching historic proportions, the anger fuelled, of course, by lamentable results but also a sense that nothing profound is going to change with billionaire Dermot Desmond as major shareholder and of no mind to go anywhere.

As a city rival, Celtic folk took great humour from Rangers' travails for most of the season - their slapstick signings, their ex-manager smuggled out the back of a stadium and then fired, their dismissal of Kevin Thelwell and Patrick Stewart, two major figures at the club. Despite all of that, Rangers are now level on points with Celtic. Both of them are trailing Hearts. At least Rangers have had their purge, their moment when they accepted with a bit of humility that they had made mistakes and that the manager, the sporting director and the chairman had to go. They have a cleanish slate now. Celtic do not. They have problems at every turn.

Relieving Nancy of his duties is just part of it, but it should be the first part. Eight games is a painfully short spell in charge but there isn't a crumb of evidence to support him staying. On Saturday afternoon the wall of police and stewards holding the line between furious fans and the front door of Celtic Park was alarming. Nancy's days are numbered, you have to think. No promise of jam tomorrow is cutting through now.

If the Celtic board bring this experiment to an end, what then? The bat signal sent up for O'Neill? Maybe, but the fog of uncertainty around this club doesn't just clear if he returns. This chaos is on Nancy, but not only Nancy.