Amid the chaos of the Manchester City‘s derby defeat to Manchester United last weekend it went under the radar that John Stones was not among the hosts' substitutes. It was a dramatic fall from grace for someone Pep Guardiola has defended to the hilt in his time at the Etihad.

Yet, in a game which was very much second to their upcoming Champions League quarter-final second leg in City's list of priorities, Stones was deemed surplus to requirements; not needed in Guardiola's matchday 18. It flew in the face of everything the Catalan had ever said about the England international.

“John Stones has more personality than all of us here together in this room,” Guardiola said in March last year. “More balls than everyone here. I like that. I love him.

“Under pressure, the people criticise him, so I am delighted to have John. With all his huge amount of mistakes. I love him. I love guys with this personality.

“Because it's not easy to play central defender with this manager. It's not easy. You have to defend 40 metres behind and make the build-up.”

He was left out once more on Tuesday as City were knocked out the Champions League by Liverpool. Admittedly a spare defender was unlikely to be called upon with the Citizens having to overturn a three-goal deficit, but still, it showed where he stands in Guardiola's squad at present.

The Premier League champions-elect have no shortage of players who can break open a game; Sergio Agüero, Raheem Sterling, Gabriel Jesus, Leroy Sané, David Silva and Kevin De Bruyne have each made vital contributions, helping to make City one of the most formidable attacking teams in Europe.

They keep the ball easily, open up defences regularly and constantly find ways to put the ball in the back of the net, scoring a frankly ridiculous 130 goals in 53 outings so far this term.

It’s keeping them out at the other end that’s a problem. Yes, City boast the best defensive record in the Premier League having conceded just 24 times in 32 games. But their backline has looked anything but assured throughout the campaign – especially in the last week.

A 13-point cushion means they will soon win the title that has looked a forgone conclusion for months, but their Champions League displays highlight an on-going problem.

In the final group stage game, Shakhtar Donetsk secured a 2-1 victory that earned them a place in the last-16, the same round where Swiss side Basel won by an identical scoreline at the Etihad Stadium. Liverpool then repeated that outcome for a third time this week, while the Manchester derby saw United run out 3-2 winners just a few days earlier.

No matter what Guardiola tries, the issue remains. Manchester United got the better of Nicolás Otamendi and Vincent Kompany, while it was the latter who played alongside Aymeric Laporte in the first leg against Liverpool.

In the return clash, Guardiola opted for a three-man unit of Kyle Walker, Otamendi and Laporte. But the result remained the same; bad positioning, worse timing and gaping holes whenever Liverpool struck on the counter.

Perhaps it is time that Stones – who cost £47.5 million just 18 months ago – was given more opportunities. He has only started 14 league games this term but, with the title a formality, Guardiola has the chance to give him a sustained run in the side.

Among all City’s central defenders, the Barnsley native ranks second in terms of tackles (1.18) and interceptions (1.41) while committing fewer fouls per 90 minutes than any of his colleagues.

With the ball he is second only to Otamendi, completing 83.07 passes per 90, 28.89 of which are forward passes – more than any other defender in the Premier League. Stones' completion rate of 96.3 per cent is at least four percent higher than that of Laporte, Otamendi or Kompany.

How does Manchester City defender John Stones compare to his team-mates

With time now to build familiarity with one another before next term when City will be even more focussed on European glory, those numbers could improve further still; his attributes have long made him a player who should thrive under Guardiola.

As Carles Puyol, Gerard Piqué and Jérôme Boateng can attest, the former Barcelona coach has enjoyed his greatest successes with indigenous players at the heart of his defence.

Stones could well continue that trend and we know Guardiola will never change his approach, a style that has often caused imported talent – even when it is highly regarded and widely coveted – to fail. Dmytro Chygrynskiy, Martín Cáceres and Medhi Benatia have all been fine defenders, but they all struggled to meet Guardiola's high standards.

Of course, nobody would be surprised if Manchester City once again splashed out on another expensive central defender in the summer. In the meantime, City have six games left. If Stones cannot force his way into Guardiola's thinking in that time then it seems one of football's great love affairs could be at breaking point.

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