John Collins, the Celtic assistant manager, looked to paint a picture with his words as he reflected on an abysmal European campaign this season; “You can either have it black, white or grey. The black is we’re out, two points, absolute disaster in some people’s minds,” was his summation. The danger for Collins is that the canvas appears cohesive only to the artist’s eye.

Collins bristled at the suggestion that had Celtic’s philosophy been more pragmatic they may well have enjoyed a much more fruitful campaign, yet he admitted a candid acknowledgement that a porous backline which leaked 11 goals in five games could effectively come at a cost more significant than exiting the competition. Deila was backed publicly by Peter Lawwell, the Celtic chief executive, only last week at Celtic’s AGM but the ultimate question to be asked is whether or not this is a coaching unit that can be trusted with a third crack at leading the club into the UEFA Champions League group stages.

“We can't go and buy a Champions League player on our budget so we have to learn in Europe by making the mistakes and not repeating them,” said Collins.“And if we keep repeating them then we’ll probably not be here - players, managers, coaches.” It was the most logical analysis of the situation.

Many would laud the philosophy shared by Deila and Collins as commendable. But ultimately, it is successful only if it yields results. The scalps Celtic have taken post-millennium under Martin O’Neill, Gordon Strachan and Neil Lennon – and they are weighty in name – have all come through a game plan that preached a sober sense of caution. Deila’s favoured 4-5-1 system has been criticised not only for leaving Celtic too open but also because of the rigidity with which it has been applied.

Collins, though, was unequivocal in his defence of the way Celtic have been set up, instead insisting that the individual mistakes that have proved so costly can be fixed on the training ground - assuming the management team are allowed the time to do so.

"What do you call pragmatism?” asked Collins. “Have we been playing top European teams? If we set up 4-5-1 against Malmo, Fenerbahce, Ajax, Molde would you guys and fans be happy if we sat in? We believed after watching, analysing and assessing our opponents that we could go and play them at football, toe to toe, and beat them.

“I think the system suits our players. The results wouldn’t suggest that - but the performances within the results? We’ve conceded goals but the system has nothing to do with us losing three goals to set pieces against Malmo.

“Players not picking up in the box, not challenging, maybe not stepping forward - they're details you have to learn. We do our homework Monday to Friday, we sit a test on a Saturday, but the test we sits midweek, we’ve not had the results.

“We lost the ball on the edge of our box [against Ajax] - is that a fine margin? Is that tactics, the wrong shape? We’re up for a corner, a player gets caught on the ball, they counter attack - is that down to the system or is it a mistake? You have to analyse the goals. A misplaced pass, intercepted. That’s not the system. That’s errors within the system.”

It would be labouring the point to say that Celtic supporters saw red on Thursday night as Deila’s side moved to their tenth successive Europa League defeat. There was a smattering of boos within the ground as Ajax made off with all three points, but ultimately the anger was released when the damage was done in that limp double header against Molde that so shaped Celtic’s campaign. By the time the whistle sounded on Thursday there was a tacit resignation that the club had met their inevitable fate.

The final group game against Fenerbahce in Istanbul next month will serve as little more than a statistical footnote for Celtic. It will be the final European venture until the next round of qualifiers this July and while it remains to be seen if Collins and Deila are there to oversee those games, Collins has called on the Parkhead players to show in every game the habits which he expects are fundamental to any progression.

“How do we prepare for Europe? We make sure we are on it when we lose the ball in every league match. It doesn’t matter if we are 3-0 up,” explained the coach. “When we lose the ball we have to react and get tight, as if we were playing against a Champions League team. That’s the habit we have to get into, no matter who we are playing.

“We are winning 3-0 regularly and sometimes we don’t sprint back into our shape, so were into bad habits. When I spoke about the other teams, I didn’t mean to be disrespectful. It was a message to our players - don’t get into bad habits. We need to do better, without the ball. With the ball, we are a useful team.”

The jury remains out on just how useful.