“There are ex-players and ex-referees being given air-time who I wouldn’t listen to in a pub,” was Keane’s most famous missive.

How ironic, then, that on ITV in England Keane became the ranter extraordinaire of English punditry, not afraid to pass comment on anything and everything that makes him angry. And an awful lot made him angry.

Celebrating finishing fourth? You should be embarrassed. Rolling around having been fouled? Have some self-respect.

A non-macho player being made captain? You are kowtowing to the weak-willed. Flash players? Killing the game.

To many, Keane has become a TV pundit doll — pull out the cord and watch him go. If there is one thing that Keane is brilliant at producing, it is headlines. Most will contain the word ‘blasts’.

But as he leaves his role as Ireland assistant manager, having been part of a coaching team that has overseen Nations League relegation and a miserable record of four goals and a single victory in nine matches in 2018, Keane may well wonder where it all went wrong.

It may cause steam to be expelled from his ears, but Keane is now a more successful pundit than football manager.

It was not that O’Neill and Keane’s reign was a disaster.

No manager of a national team dealing with such significant structural issues in the domestic game and an increasingly shallow pool of talent can be accused of that.

But successful Ireland management teams have either punched above their weight or stirred a pride within the team that spurred the players on.

During 2018, O’Neill and Keane have done neither. This Ireland team are wincingly predictable and easy to defend against.

It leaves Keane with a sparse CV. His Championship Manager of the Year award, earned after winning promotion with Sunderland, was over 11 years ago and seven months after receiving that honour he had resigned.

An 18-month spell at Ipswich Town was mediocre at best, while Keane comes out of the Ireland job with very little added to his reputation.

If the victories over Germany in Euro 2016 qualifying, Bosnia in the playoffs and Ireland at the tournament itself were the notable high points, Ireland have won two competitive matches in the last two years, against Wales and Moldova.

Keane’s problem is the growing suspicion that he is not worth the hassle. 

During his time with Ireland alone, the publication of an autobiography shortly before two crucial qualifiers in 2014 caused controversy, he had a public row with Everton chairman and manager Bill Kenwright and Roberto Martinez and he stated that Daryl Murphy, Jeff Hendrick and Aiden McGeady were fortunate to get into the Euro 2016 squad.

A row with Harry Arter and Jonathan Walters in training led to Arter taking a temporary step back from international duty.

It’s hard not to view all of this as an unnecessary and unhelpful distraction — assistant managers are best seen but not publicly heard.

There is nothing wrong with any coach speaking his mind, but Keane’s managerial ethos now strikes as distinctly passé.

The sergeant major act feels out of place in an age when micro man-management and player morale has never been more crucial.

He feels like an anachronism, angrily telling the television audience and players why it wasn’t like this in his day. Doing that can quickly date you.

Keane was a magnificent footballer, perhaps even the most complete midfielder of the Premier League era, but that will count for little if he wishes to continue his club career, probably in the Championship.

If his power to inspire players still remains, it will take a leap of faith from any club owner to believe him worth the likely fuss.

It’s now seven years away from the Football League and counting.

But the alternative is that Keane continues his successful punditry career until it becomes the full-time project.

Does that not threaten to make him everything he previously affirmed to dislike?

Roy Keane has a personality that dictates he will never truly fall off the radar — he is a headline-maker.

But that persona threatens to hold him back as much as propel him forward. Post-Ireland, he faces a hard battle for the sort of relevance he would like.

If that sounds blunt and slightly damning, it only judges Keane by his own rules.