SO that is that for the great Celtic rebuild. It was a case of revolution, not evolution, for new Celtic duo Ange Postecoglou and Dominic McKay, as manager and chief executive attempted to salvage what they could from the wreckage of last season’s squad, while replacing the 13 players who left the club.

Twelve players arrived at Celtic, and as far as the balance sheet goes, no doubt McKay and his boardroom colleagues will look upon the summer window as a roaring success. The sales of Odsonne Edouard and Kristoffer Ajer were the significant drivers that helped push the incoming total towards the £34m mark, while a shade under £20m was laid out on transfer fees.

As well as Edouard and Ajer, captain Scott Brown, Moi Elyounoussi, Diego Laxalt, Jonjoe Kenny, Armstrong Oko-Flex, Jack Hendry, Vakoun Issouf Bayo, Marian Shved, Olivier Ntcham, Leigh Griffiths and Ryan Christie all departed.

Coming the other way were Osaze Urhoghide, Liam Shaw, Liel Abada, Kyogo Furuhashi, Carl Starfelt, Joe Hart, James McCarthy, Josip Juranovic, Liam Scales, Giorgos Giakoumakis, Filipe Jota and right at the death, Cameron Carter-Vickers on loan from Tottenham Hotspur.

“From the skill and experience the likes of Joe Hart and James McCarthy bring to the squad, to the flair of players like Kyogo and Liel Abada, this transfer window has been a busy period for the club with 12 new players joining Ange and our squad at Celtic,” McKay said yesterday.

“We have strengthened the squad in all areas of the pitch, with international-level talent, and while naturally disappointed to see some faces head in the opposite direction, we wish them every success in their next ventures.”

The obvious question to follow up McKay’s assessment of the success of the window from Celtic’s perspective is whether it was shared by Postecoglou, who had publicly called for further backing when his side crashed out of the Champions League qualifiers to FC Midtjylland earlier in the summer.

His utterances on the topic so far have been limited to the official club website, so it is little surprise to see that they chime with those of his chief executive.

“Everyone at the club has worked hard on making really good progress in this window and I am really pleased with the depth of quality we have managed to deliver,” Postecoglou said.

“I think the squad is in good shape for the challenges ahead and I look forward to get working as a unit with the whole squad together, as one, after the international break.”

Perhaps the most pleasing thing for Postecoglou, and maybe most vital, is that he has jettisoned the players who caused an issue for predecessor Neil Lennon by their very presence last season, when they would rather have been elsewhere,

“While so many players have come in, I would also like to thank the first team guys who have moved on from Celtic, for their contribution to the club,” he said diplomatically.

“Odsonne and Ryan are two players who have been fantastic for the club over a number of years. They wanted to look at new opportunities, I am sure they will continue to have very successful careers and I wish them well for the future.

“I also wish Leigh well on his loan spell at Dundee, where I am sure he will get back into some important playing time.”

The proof of the success of the window of course will of course be in the pudding. Let’s not forget that around 12 months ago, what turned out to be a disastrous summer window was lauded by the vast majority of supporters and pundits.

So, judgment should be reserved for now, and the players brought in given a fair crack of the whip to prove themselves. That being said, while there have already been some notable early successes among them, there are some areas of real concern too.

Depth in the centre of defence will be provided by the return of Christopher Jullien later this month if his recovery schedule goes to plan, but left-back still looks a little light with only Greg Taylor and Scales.

The midfield area too may be heavy on bodies, but there doesn’t appear to be a viable alternative to Callum McGregor should the Celtic captain get injured or require a rest now and again. It may be asking a lot for McGregor to go to the well and churn out 50-plus appearances yet again this season, and it would represent a major problem for Postecoglou should he break down for any length of time.

A little further ahead, a lot will also be asked of David Turnbull and Tom Rogic, though the wings do look well stocked to avoid the issue that James Forrest’s injury woes created last term.

Up front, the arrival of Giakoumakis should take the pressure off Furuhashi, while the underwhelming Albian Ajeti will provide the back-up.

Postecoglou has already intimated that he will look to exploit the Japanese market in January, so perhaps these issues will be resolved then. The task for this group of players is to stay in contention until that can happen.