With an eloquence and a pithiness many of us can only envy, a complex issue was perfectly distilled last Saturday.
'We're not fickle. We just don't like you,' read the message one Aston Villa supporter conveyed memorably. In the unlikely event that there is a 'banner of the season' award, this was the runaway winner. On a bright orange backdrop, it was impossible to miss.
At every step, O'Leary's arguments have been forensically deconstructed.
Jeered in the 4-1 thrashing at Everton, he claimed it was the only time he had been booed in 30 years. A week later, Villa supporters ensured that is no longer the case. Then, the Irishman's glib assertion that only two fans out of 32,000 opposed him was challenged; over 4,000 supporters bought badges proclaiming their opposition to their manager, though an embarrassingly one-sided match at Highbury commanded the attention instead.
An attempt at a charm offensive, to them, reeked of insincerity. Displacing Doug Ellis as the more disliked member of the manager-chairman partnership is a rare achievement, but O'Leary appears to have managed that. Indeed, he has an unfortunate habit of antagonising people as former team-mates Niall Quinn (who likes the Villa boss) and Tony Cascarino (who does not) admitted in their autobiographies. Even Sven-Goran Eriksson may not like him, to judge by his apparent willingness to take O'Leary's job.
That extends to the media. In both Yorkshire - a remnant of his time at Leeds - and the West Midlands, adversaries abound. Accusing the Birmingham Evening Mail's Villa correspondent of supporting West Bromwich Albion and banning him from press conferences was not, O'Leary may reflect, his most diplomatic move.
None of this necessarily makes O'Leary a poor manager. Indeed, uniquely among current British managers, he has never finished below the top half of the Premiership. That, however, will soon change as Villa's downward curve from the overachievement of his first season (when they came sixth) to underachievement continues.
And, while O'Leary insists his detractors are stuck in 1982, when Villa won the European Cup, the nostalgics don't have far to hark back to for something approximating to success; this is a club with nine top eight Premiership finishes, now languishing in 16th. As long as Doug Ellis clings to the reins of power, another appears unlikely. That O'Leary's rhetoric on talk of takeovers has changed from the encouraging to the downbeat may reflect on the precariousness of his position; would any new owner want to be saddled with such an unpopular manager?
And Ellis, despite the tag 'Deadly', has not sacked a manager since 1994; his uneasy alliance with O'Leary may have been cemented by a downturn in results. For such an accomplished defender as a player, his team display little of the composure that was once O'Leary's hallmark. At both Everton and Arsenal, goals were yielded that would make George Graham wince.
If a reputation for defensive competence is being shattered, the unwanted tag of a chequebook manager is yet to be shed. But at Villa Park, early signings - Gavin McCann, in particular - were workmanlike; more recent arrivals have been conspicuously unsuccessful. Eric Djemba-Djemba has contrived to have both a negligible and a negative impact.
Mathieu Berson, if one fans' campaign succeeds, could be crowned Villa's Player of the Year, a protest vote relating to his apparent excellence on loan at Auxerre and his earlier anonymity at Villa Park (spare a thought for James Milner and Steven Davis; neither has a trophy cabinet that is exactly bulging, and both would be worthy winners).
But both individual buys and O'Leary's transfer policy are being questioned.
His summer decision to spend £10 million, the bulk of a hefty transfer budget, on two flagship signings has backfired; Wilfred Bouma has been no more successful than Villa's other defenders and Milan Baros, while maintaining an acceptable if unexceptional goal record, equipped himself with a release clause and appears to be eyeing a move away.
That was five months ago. With Ellis' tacit backing and the likelihood that there will be no change at the helm while the ownership of the club is being resolved, opposition has taken the form of unrest rather than the expectation O'Leary will be sacked. If Villa can contrive to embroil themselves in the relegation battle, his opponents will be still more numerous.
There is a tendency, fuelled by phone-ins and message boards, for knee-jerk reactions. Yet, among Aston Villa supporters, there is a greater consistency than many of their rivals display. Arguments have been rehearsed and developed over years. Many have come to regard O'Leary as a serial moaner whose excuses lack credibility.
Even at a stagnant club with a seemingly permanent air of negativity, the institutionalised defeatism that O'Leary presents as realism grates with supporters who have higher aspirations. Forget 1982, their first objective is to match Wigan and West Ham, Bolton and Blackburn, clubs who, with lesser resources, are enjoying superior seasons. Those opinions will not change.
They're not being fickle. They just don't like him.