Wednesday, 30 March 2016

Most Football Managers Don't Make Much Difference, You Know!


I noticed some Liverpool fans in a sports forum eagerly anticipating next season under new manager Jurgen Klopp. They were hopeful that the Klopp-factor would bring success where other managers had failed. I’m afraid I was a Cassandra figure who pointed out to them that in all likelihood Klopp’s arrival won’t make much difference to Liverpool’s success, because managers generally don’t have much of a bearing on a team’s success (for more data on this, Google the studies done by the Dutch economist Dr Bas ter Weel). Notable exceptions in Premier League history are probably Alex Ferguson, Arsene Wenger and Jose Mourinho, which is interesting given that one has retired, one is under constant pressure to be sacked and the other was actually sacked earlier in the season.

I'm sure anyone vaguely interested in football will recall times when a new manager comes in and apparently works his magic, supposedly turning things around for the better. It happened at Manchester City with the arrival of Roberto Mancini, and it's happening now at Chelsea with the arrival of Gus Hiddink. It's certainly true that some new managers have a honeymoon period on arrival, but I think they are rarer than you imagine. And even when they do occur, something else is actually happening - something more to do with probability than magic managers, as I'll explain.

In simple terms, if you're a team doing worse than expected, the chances are you are soon going to improve, irrespective of whether you sack the current manager or not. For the best example of this, take Chelsea, the club most notorious for sacking managers halfway through a season. A quick check on Chelsea’s results since the year 2000 shows that they average 1.7 points per game. As you’d expect, if you take Jose Mourinho’s bad string of results this season they fall a bit below the average, whereas if you take Gus Hiddink’s (the manager who replaced him), they rise a bit above the average.

Mourinho was sacked due to a poor run of results, but even if we overlook the most important fact – that Mourinho is a world class manager with a proven track record of success – had he not have been sacked and replaced by Hiddink one would have expected his next set of results to be better than the last. This is called the regression to the mean. If you a measure a series of results (say Mourninho’s) and they are lower than Chelsea’s average then it is expected that measuring the next series of results should see them tend closer to the average. In other words, Hiddink's relative success is about his being the beneficiary of regressing to the mean after Mourinho’s poor run of results – it is highly unlikely that his arrival had any major overall effect on performance, save for the inevitable short-term ‘work hard to impress the new manager’ phenomenon which lasts no more than about 3 games.

Given that most managers don’t have much of a bearing on a team’s performance, sacking them is obviously a costly exercise. Not only is there the expense of paying off the sacked manager, and the extra expense of employing a new one, there is also additional expense as new managers inevitably want to be given a spending pot in order to sign new players and build their new team with players they've bought.

If this is so costly, why then do football clubs sack their managers with such regularity? The obvious reason is that sacked managers are an ideal scapegoat, which gives everyone someone to blame for the failures, and it gives the fans renewed optimism (albeit false optimism) after a slump. The truth is, in most cases there is little to be optimistic about when a new manager comes in, as most won't make much of a difference to your team's results, and will, in fact, probably cost a lot more than the overall value they bring.  
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