IT costs a lot of money to stand still in European football.

Celtic broke their transfer record last summer and the wage bill at the club is the highest it has ever been, and yet Brendan Rodgers’ side are no further forward – in terms of the Champions League and Europa League – than when the manager first arrived in Glasgow.

Much of this is not the fault of Rodgers, his players or the Celtic board. This is football in the 21st century. A Scottish club, even a rich one which dominates their own league, is a minnow compared to the team sitting eighth in La Liga.

That is Valencia. In European terms they are a top-20 club most years, they were unfortunate to finish third in their Champions League group, and yet without some of their best players found Celtic far too easy an opponent in their 2-0 win in Glasgow on Thursday night.

It is nights such as this which will nudge Rodgers closer to the exit door. There is only so much a coach can do, although the manager is not above criticism. It is commendable that Celtic try to play out from the back against far superior teams. The problem is that tactic does not work.

If you look at the Celtic players on the pitch in midweek, realistically Callum McGregor is the only player who can move up a level. The rest are either at their peak or on the way down. This team as a whole is not going to get any better unless the board spend £30 million in the summer.

And even then, such an unlikely outlay is not going to make Celtic so much better that they could expect to see results improve even by a small margin.

“The money gives you belief,” said Rodgers when asked to explain the difference between Valencia and his own side. “Otherwise, with all due respect, lesser players would be up at that level. If you have players of that quality, and a big number of them, they have a belief. Sometimes ability-wise there isn’t a big difference, but the belief carries them absolutely to a certain stature.

“That’s the difference between a lot of the players at that mixed level. But for us, Thursday was disappointing because we are a lot better than that. It was our own mistakes. It wasn’t as if they were peppering our goal or speeding up their game or even cutting through us.

“Games like that one are going to be tight, but you can’t make mistakes. And we did that too many times.

“The players aren’t bad footballers. Absolutely not. It’s just a certain level that you can go to. It’s as simple as that. The level is not only belief, it’s also concentration.

“As you go through the levels, you can see that concentration, and for us it was unfortunate that one or two errors with concentration cost us.”

Celtic made the last 32 of the Champions League under Neil Lennon in 2012/13 season. That was largely down to beating Barcelona, a result which sits comfortably within the club’s top-10 nights.

And you need to go back to 2004 when they last got through a knock-out tie when, hey, they beat Barcelona.

For all that Celtic are at a financial disadvantage, they should be able to do better than they have done in some games under Rodgers. For all Valencia were impressive, they were helped by a side which had forgotten how to pass the ball five yards to a team-mate.

Rodgers put on a brave face at the end of it, even suggesting his side were still in the tie, but even he could not hide a sense of resignation that for all his good work, for all that Celtic are not a bad team, they are well short at the level needed to beat a Valencia side not having all that memorable a season.

“It was a difficult night, a disappointing night in the end,” admitted the Northern Irishman with a shrug. “We had a good start in the game, I thought we were looking well, we passed the ball and were confident with what we were doing. We broke up the pitch and got into good areas.

“The problems came for ourselves when we started making basic errors. We built pressure on ourselves by making poor choices and poor passes. It was very unlike us because normally we are clean with our passing, and the problem is if you do that against good team they punish you.

“There wasn’t a lot of chances for either team. Valencia sit in, they are compact, they are tight, and wait for mistakes. For us, we made too many.

“What happens when you make mistakes as we did, you kill your own momentum. The momentum in the games goes, the flow goes. And then you start to play safe. It’s a sideways pass, a backwards pass. We lacked a wee bit of belief.

“For all of that, we should have got through to half time. We make a crazy decision of trying to play off-side. From there, playing a team which defends well, you’re up against it.

“We will dust ourselves down. For us, we made a really good fist of getting through the group with 10 points, which was great for us considering the group we were in. We still have another leg to go.

“If we can get the first goal out there, you can see that if we don’t make the mistakes then we’ll have the opportunities. But if we can get that first goal it might just give you the belief to go and get something.”

Rodgers did not criticise his players in public even if some of the errors were awful, which was damning in itself. Put simply, why have a go at anyone whose best is not good enough?

“The thing about my players is that for the last two-and-a-half years they have played 60 games a season,” he said. “They’ve given me everything. I have absolutely no complaints.

“If you try to just match up against better players then the likelihood is you will lose. Part of the development here since I came to Celtic was to have a blueprint that allows you to try and do it differently.

“Yeah, sometimes we will lack at that higher level which I can understand. And especially at the level we play. Sometimes you have to try and bridge that gap however which way. You have to find a way of playing.”

Whether Rodgers will be here next season, still trying to find a way to play against the Valencias of this world, remains to be seen.