He did it his way, and it made Roy Keane unique. It also led to a premature departure from his beloved Manchester United; even to the last, Keane had not lost his capacity to surprise and even shock. Sir Alex Ferguson and Ruud van Nistelrooy paid generous tributes; admiration was unconfined at Old Trafford for their combative captain. And, it appears, at many other clubs.
Keane's sudden release could circumvent the transfer window. It has certainly prompted one of the most intriguing battles in modern football; supposed suitors range from the new leagues of Qatar and the USA to Juventus, matriarchs of Italian football, and his boyhood heroes Celtic, not to mention much of the Premiership.
But which Roy Keane would they get? The dominant force of 1999, surely still remembered in Turin for his tour de force in the Champions League semi-final, is gone. Physical decline and injuries have taken their toll, and his lung-busting runs are confined to the past.
More recent features of Keane's career include the MUTV show that wasn't and the World Cup that, for him, never started. Given the reasons for his row with Mick McCarthy, it seemed somehow odd - or a little desperate - that Portsmouth, noted for their rather antiquated training facilities, were the first to declare an interest in Keane.
And an interpretation of the dissolution of Keane's relationship with Ferguson is that, ultimately, captain had higher standards than manager. Hence piercing criticism and the descent from his master's voice to loose cannon. But, though the targets of Keane's ire - players like Rio Ferdinand, Alan Smith, Darren Fletcher, Kieran Richardson and John O'Shea - have hardly cemented their place in United folklore like their former captain, each is an international.
So a willingness to bawl out multi-million pound signings may cause tremors in dressing rooms across the country. A lesser talent - and from Andy Griffin to Darren Moore, from Stuart Parnaby to Tony Hibbert, there are plenty who may be imagining themselves lining up alongside Keane - could be picked upon for playing as well as their limited ability permitted.
And as the fragility of team spirit could be exposed by a Keane tirade, should his volatility be a deterrent? Or, indeed, his own managerial ambitions? The Irishman may not pose a threat to Sam Allardyce or Steve McClaren but others may ponder the wisdom of hiring a potential successor.
So much for Keane's character; what about the player? Short of having 'winner' tattooed on his forehead, Keane could have done little more to separate himself from players he judged lacking in ability or desire. But his credibility as a critic could be called into question if the Irishmen were unable to get into the team he so royally condemned.
Manchester United's successful reversion to 4-4-2 may have come at Keane's expense. Ferguson tried to accommodate his captain, despite lesser mobility and more frequent absences, but it resulted in a change of system; would he have been discarded if the Scot still regarded the Irishman as an essential element of his side?
So Bolton and Everton, each accustomed to playing with an anchor midfielder, could be logical destinations. Aston Villa and Birmingham, however, would require a tactical alteration.
And while Keane's sudden availability prompted suggestions that 19 Premiership clubs would beat a path to his door, half of the division, realistically, can be counted out. A Keane-McCarthy reunion at Sunderland would be box-office material, if sadly implausible. Though Arsene Wenger, intriguingly and mischievously, refused to rule out a move for Keane, London seems an unlikely destination.
Though the Lancashire high-flyers of Wigan and Bolton are notable exceptions, the majority of the other options involve a fight for survival.
Keane lost his only previous relegation battle, with Nottingham Forest in 1992-3. Pitching him into a demoralised and out-of-form team could be a masterstroke and might be incendiary; it would certainly be compelling.
And it would probably involve facing Manchester United, something he vowed never to do. Leaving the Premiership, of course, would preclude this, and Celtic has long seemed his preferred move. But Gordon Strachan has been non-committal and, though there has been a core of senior players in each of his teams, their loyalty has been of paramount importance to him. Neil Lennon, in any case, plays the Keane role at Celtic Park.
The alternatives are more diverse. For such a competitive man as Keane, would a final pay-day in the Middle East, no matter how lucrative, have much appeal? In contrast, the lure of Juventus is unquestioned; however, they decided they were not looking for an understudy to his old adversary Patrick Vieira and Emerson. It means Keane's next club, wherever it may be, will hardly be comparable to Manchester United.
So could he adjust, whether to a struggling side or a lesser league? Compromise has rarely seemed to be a word in Roy Keane's vocabulary. An intimidatory presence for team-mates and opponents alike, his single-minded pursuit of excellence has precluded perspective and coupled with a self-destructive streak, led Keane to this crossroads in his career.
Seemingly, there are plenty brave enough to sign him, though his searing honesty and creaking frame make it a risk - but is he still a risk worth taking?
•Email firstname.lastname@example.org with your thoughts.