History only repeats itself when people fail to learn the lessons of the past.
So it is with Sheffield United who are making the same mistake with Chris Wilder as they did with Neil Warnock in 2007.
United blundered big time when they let Warnock quit in the wake of their last relegation from the Premier League.
Warnock was devastated to see his beloved Blades go down on the last day when they lost a relegation shoot-out in the rain to Wigan.
He felt utterly let down by the Premier League for refusing to deduct points from West Ham over the Carlos Tevez affair and by Manchester United for fielding a weakened side to allow the Hammers to win at Old Trafford on the final day and survive.
But most critically, he felt let down by what he saw as a lack of support from the Blades board and quit in disillusionment.

The Blades foolishly accepted Warnock’s resignation instead of telling him to take time to consider his future rather than decide it in a moment of anger.
Even more foolishly, they appointed Bryan Robson as his replacement, who was the wrong manager for the wrong club.
Sure enough, Robson failed and was sacked within nine months and the Blades spent the following 12 years outside the top flight, including six in League One, until Wilder revived them.
Just as Warnock would have been the ideal man to lead United back after their relegation in 2007, so would Wilder have been the perfect manager for them next season in the Championship.
But instead a wedge developed between Wilder and the board over their conflicting views on the club’s future direction and he went.
There is blame on both sides for the breakdown in their relationship and the board were right to question Wilder’s transfer record after so many flops.
He was also right to demand the right to retain full control over all football matters because of his success over his five-year reign.

The upshot is that everyone loses.
Wilder has left his beloved Blades, the players are devastated he has gone – as evidenced by their white-flag display at Leicester – the fans are gutted to lose one of their own, and the board have lost the best man to manage them.
Warnock can see parallels with 2007 and Chris Sutton fears United could be relegated to League One by the end of next season.
Sutton’ warning should be heeded and United operate in extreme cycles of boom and bust.
After finishing sixth in the old Division One in 1975, within six years they were in Division Four.
Similarly, after enjoying four years in the top flight under Dave Bassett at the start of the 90s, they endured 12 years in the Championship.
They suffered a bigger fall after being relegated in 2007 and spent between 2011 and 2017 in the third tier.
Hopefully history will not repeat itself again, but it will if United keep making the same mistakes.