There was more than just a sense of a changing of the guard in this transfer window for Celtic.

A dozen new arrivals have gone into the club under the watch of Ange Postecoglou these past few months but perhaps just as significant has been those who have headed out.

Leigh Griffiths’ comments as he checked into Dens Park this week did more than just raise an eyebrow.

Having struggled to nail down a consistent start under the trio of managers who followed Ronny Deila, Griffiths took a pop at Neil Lennon as he checked into a loan spell at Dundee.

It is more than six months since Lennon left Celtic. The ink had no longer dried on the extra year Griffiths had signed with the club and he was blotting his copybook under the eyes of a manager who lends an impression of not suffering fools gladly.

It is no surprise that after being booed by the Celtic support after again finding himself making front-page headlines instead of back-page ones that the clock was ticking on Griffiths. But his remarks upon his exit offer an insight into the atmosphere that would have been at the club last season given the levels of discord within the dressing room.

READ MORE: Celtic's best certainly yet to come in the Ange Postecoglou revolution

Odsonne Edouard’s body language was the subject of much discussion over the last twelve months, some of which was overcooked at times, but it is a while since Celtic would have seen him sport a grin as wide as the one he showed for the cameras at Crystal Palace.

Ryan Christie’s fury at Ibrox on Sunday as Kyogo Furuhashi went for goal instead of squaring the ball may have owed something to the fact that he would have been keen to depart having left a decent farewell gift.

But the long and short of it is that while Celtic will laud the various contributions of all three – and in Griffiths’ case rue what else might have come from an instinctive penalty box striker – there is no chance of building for the future when there are eyes on the door.

As the window closes until January there is a feeling that so much of the unease around the club has been replaced with a sense of certainty.

It got its biggest dent over the last week with the defeats to AZ Alkmaar and Rangers but it would be difficult to underestimate the magnitude of the rebuilding that has taken place in a relatively short time.

There is a clear philosophy implemented in the identity of how Celtic will play with little suggestion there will be a deviation from it, regardless of opposition. Whether it succeeds or fails remains to be seen but the early evidence would point to everyone singing from the same songbook.

Without that sense of unity, any manager swims against the tide.

Restoring dressing room stability is as pivotal as any work that has been done on the Lennoxtown pitches.