Or, were expectations simply set too high after they over-achieved last year by reaching the last 16 of the Champions League and adding another league and cup double to the record books?
The answer lies somewhere in between.
Certainly, it was always going to be very difficult to match last season's achievements in Europe.
But, having said that, with the squad Neil Lennon has at his disposal, back-to-back doubles should not have been beyond them. And I say that fully acknowledging that history shows it is never an easy thing to do.
I know Neil - who I met this week when I took a group of students to Lennoxtown - will be feeling disappointed by the manner in which his team went out of the Scottish Cup at the weekend.
Now his players will all face a severe test of character to pick themselves back up on Sunday when they run out against St Johnstone at Celtic Park, because I do not expect to see many more fans turning up for games than the half-full house which witnessed the defeat to Aberdeen.
The supporters feel let down, and the players have to realise that.
However, as well as the fans, they let themselves and their manager down with that performance last weekend.
The defeat, coming less than 24 hours after the club announced such healthy financial figures, has caused a predictable outcry from fans who believe more money should have been invested in the team over the course of the last two transfer windows.
With a club the size of Celtic, it is very much a balancing act between what you achieve on and off the park.
Occasionally, however, you have got to tilt it in favour of one, and I believe it should have been loaded a bit more towards the playing personnel.
I am not talking about putting the club in any kind of financial jeopardy.
But chief executive Peter Lawwell spoke about being in a position to spend £8million on a player.
The fans leaving the ground after watching last weekend's defeat were asking, 'Well, why didn't we?'
The truth is, however, that, while you might be able to afford that kind of transfer fee, it is another matter to be able to afford the wages which go with such an acquisition.
This is where I would like to see a bit of tweaking, in terms of the wage ceiling - and that includes some of the top players who are already at the club.
No one knows for sure how much more Gary Hooper was looking for to stay at Celtic last summer, or, indeed, if no size of a wage increase would have persuaded him to hang around for another season or longer.
What does seem clear, though, is that the club have not been able to put together the offer to persuade a top striker to come here as his replacement.
So perhaps it might have been the right time to go that bit further than you would normally to hold on to Gary.
With Victor Wanyama and Kelvin Wilson also sold for good money last summer, it meant Neil was having to try and rebuild the spine of his team while preparing for the most crucial games of the season, the qualifiers and play offs for the Champions League.
Players like Virgil van Dijk were still trying to settle in when they were facing Shakhter Karagandy in the play-off ties.
And no one needs any reminding how close that came to being a real disaster, in terms of Champions League participation for this season.
This summer, it could be the same again if key players are sold.
Neil has made it clear he is all-but resigned to losing Fraser Forster, while Virgil has had such a good debut season that he is sure to attract good offers.
But you can't keep on chopping and changing your team and expect success.
I know and understand the business argument. But, there is a football argument, too. Fraser could already be at the stage where he is convinced that, for his international future, he has to move.
But the cub should perhaps consider getting Virgil in now and offering him a bit more money to stay a while longer. He is only just here, after all.
Players can sometimes put pressure on a club to let them go, if their heart and ambition is elsewhere. But it is always worth trying to persuade them.
The bottom line is that, if Virgil and Fraser are sold, the team will probably be worse off than they were this season.
Neil will always push the club to hold on to their best players, and ask for the wage structure to be tweaked in exceptional cases. I can also appreciate the other side of the argument.
But it has now come to the point where the club almost can't afford not to loosen the purse strings because the prospect of not having the calibre of players required to qualify for the Champions League is so frightening.