Steven Naismith was the last straw. We could make allowances for Branislav Ivanovic getting roasted by Jefferson Montero, Raheem Sterling and Yannick Bolasie - they’re all fine wingers on their day. But the sight of Chelsea’s formerly bulletproof defender meekly turning his back as Naismith struck Everton’s second goal at Goodison Park on Saturday, as if trying to protect himself from a plummeting asteroid rather than a Scotsman’s 20-yard pea roller, was the final confirmation that the Premier League-winning footballer we came to know and/or love as Branislav Ivanovic is no longer with us. He has been somehow replaced by an inferior model. But what has prompted this alarming demise?

It’s not a stretch to say that Ivanovic has been Chelsea’s best defender of the last five years. Tougher than Gary Cahill, younger than Ashley Cole, more creative than Cesar Azpilicueta, less ridiculous than David Luiz, less promiscuous than John Terry. Ivanovic has marshalled the right side of Chelsea’s defence like a no-nonsense Chinawhite bouncer, dismissing all unwanted entrants with controlled yet frightening aggression.

This May, he was collecting a richly deserved championship medal. Yet four months later, he looks a husk of his former uncompromising self. Ivanovic’s implosion is made even sadder by his previous aura of indestructibility. It’s like seeing your dad cry or watching Batman struggling to open his emails.

So what happened to Ivanovic over the summer that may have triggered his loss of form?

Clues are sparse. The only notable change in his life was being appointed Chelsea vice-captain in July following the departures of Petr Cech and Didier Drogba. He said at the time: “I am so happy. This is something extra for me, more responsibility, and I will try to do it well for the team.”

Ivanovic is also entering the final year of his contract and had been linked with moves to Bayern Munich and Paris Saint-Germain. But nobody expected those rumours to materialise, and the offer of a new Stamford Bridge deal seemed a formality.

Analysing Ivanovic’s performance data tells us that, while his interceptions, passing and tackling stats have not altered dramatically, he has been far more vulnerable to dribbles. Whereas last season he was beaten by a dribble on average 0.4 times per match, this campaign the figure has rocketed 500 per cent to two per game. Greater susceptibility to pace is one explanation, but can a player get that much slower in four months?

This sudden rapid deterioration is as clear as it is baffling, leading us to conclude that something else has happened to Ivanovic. Perhaps something neither us, nor his manager Jose Mourinho, could begin to understand.

The first possibility is that the man playing right-back for Chelsea is not Ivanovic, but merely someone who looks a lot like him. The second is that Ivanovic took an expensive summer holiday as a space tourist, meaning that although only minutes passed on Earth while he was away, Ivanovic himself has aged several years due to gravitational time dilation. The third option, albeit unlikely, is that Ivanovic is appearing in an episode of the TV series Quantum Leap and his body is currently occupied by former scientist Sam Beckett, who is struggling to get to grips with being a top-level soccer player. The fourth and final possibility is that Ivanovic’s body is the same as it always was, but he has undergone a revolutionary operation to switch brains with someone else. This would most likely be someone famous whose body Ivanovic would pay money to inhabit, such as Martin Scorcese or Holly Willoughby, and is also evidently someone with no knowledge of zonal marking or jockeying.

And if those suggestions sound implausible, just think back to how you would have scoffed four months ago when handed a predicted Premier League table showing Chelsea fighting relegation with the worst defensive record in the division.

@darlingkevin

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