The problem with revolutions is that they take time - and modern football is a world notoriously short on patience.
If a new manager arrives and everything suddenly looks rosy then the chances are that things either were not that bad in the first place or - as, say, Sunderland have discovered - the upturn in form is temporary and a regression to the mean follows.
But if a new manager arrives and there is not a sudden improvement, there comes a time when doubt sets in.
Liverpool fans have been remarkably patient with Brendan Rodgers.
Their side sit 12th in the Premier League, having won just five of 17 games this season. There were grumbles of discontent after Saturday's 3-1 home defeat to Aston Villa, but they were relatively restrained. The sense, though, is that their faith is beginning to be tested.
There is no problem with that. On the contrary, it is right that Rodgers should be asked to explain how he considers his revolution is progressing.
But equally, having bought into the Rodgers project, it would be senseless to abandon it now.
In Brian Clough's first season at Derby County and at Nottingham Forest, he finished in the bottom half of the second flight.
Within five years he had won the league with Derby; it took three with Forest. Sir Alex Ferguson was in his seventh year at Manchester United when he won the league for the first time.
Herbert Chapman was in his sixth at Arsenal. Don Revie just avoided relegation in his first season at Leeds United; it took him three years even to win promotion.
As Ferguson has noted, in the modern world of reality television and telephone votes to remove unpopular contestants, the tendency is for snap judgements.
Rodgers is asking players to change their approach entirely. For some - notably Steven Gerrard - the new style of play is utterly alien.
If it does work, it will take time.
Of course the danger is that Rodgers is just a charlatan with a neat line in management-speak and that by following him, Liverpool have wasted two years - plus the time it takes to put right the mess he leaves.
But that is a risk Liverpool have to take. Having followed the Rodgers path this far, it makes little sense to do anything but carry on.
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