The Premier League was previously considered unique in Europe, as a top-level division in which managers were given time to battle their way out of difficulties. Whereas coaches in countries like Italy and Spain were given a few months then shown the door after a poor run of form, Premier League chairmen were more cautious, and therefore the managers more settled.
This was partly because of the difference in managerial structure. England was home to the general manager, who was in charge of everything from transfers to training to tactics. Elsewhere, there was more separation in responsibilities -- often a head coach in conjunction with a director of football.
Gradually, as football clubs expanded in size in terms of personnel and income, they started to adopt a more Continental model. The responsibilities of the manager -- or head coach -- are more limited, and perhaps they're more vulnerable to the sack.
"The British game was always very different; unique, in fact," Everton manager Roberto Martinez says. "There was a tradition that the manager decided the philosophy of the team and that is how he should be judged, not on one or two bad results. I think everyone else in Europe was a bit jealous of what we had, but in the past two years or so, we have become more trigger-happy.
"As a manager, if you are going to be a manager and not a head coach, you need time to put your ideas across, to manage your budget, to develop players for the short and long term. We shouldn't be copying other leagues, we should be preserving the British tradition."
Whatever the merits of swift managerial sackings, it's interesting how clubs decide to replace fallen bosses. Managers are now on very expensive contracts, and there's an increasing demand for them to bring in their own coaching staff, rather than work with those already at the club. This means hiring and firing a manager -- and his coaching staff -- can be an incredibly expensive process, especially if it happens every 18 months. Increasingly, the solution -- even if short term -- is simple. Sack the manager, and bring in the assistant.
The most obvious example was a couple of seasons ago, when Roberto Di Matteo took over from Andre Villas-Boas at Chelsea, and took the club to their first-ever European Cup. Typically, of course, Di Matteo didn't last much longer himself -- but it was still an extraordinary triumph, and an incredible turnaround in Di Matteo's career, having been sacked from West Brom less than a year before.
Inevitably, there were suggestions that Di Matteo conspired against Villas-Boas, something the Italian was keen to deny. "I did my best and Andre knows it," Di Matteo said at the time. "I did not conspire against him and all the decisions we took, we took together. I have always behaved with the utmost professionalism and loyalty." Villas-Boas didn't seem to hold a grudge when the two met the following season.
What Di Matteo said next, however, was most interesting. "All new managers inevitably replace a colleague when things go wrong or results are not up to expectations. This is the nature of football."
He probably meant "colleague" in a loose sense -- in the sense all managers are colleagues. Now, however, they're more literally replacing their former colleagues. Kenny Dalglish is another case -- he was involved at Liverpool's youth academy before the departure of Roy Hodgson in early 2011.
Last season it happened four times, including once again to Villas-Boas, who was sacked by Tottenham after a 5-0 defeat to Liverpool, and replaced with Spurs' former youth boss Tim Sherwood, a rather different character. Sherwood had a mixed period in charge, but his reputation -- particularly among the media -- was enhanced, and many felt sorry for Sherwood when he was dismissed at the end of the campaign. Had he plotted against Villas-Boas, who he seemed the complete opposite of? Who knows, but it was in his personal interests to do so.
Next to go was Michael Laudrup at Swansea, less than a year after winning the League Cup. His replacement was club captain Garry Monk -- initially on a caretaker basis, but he was eventually appointed on a permanent basis.
So too, was Norwich's Neil Adams. He was the club's successful youth team coach, and the obvious choice to replace Chris Hughton with five games of last season remaining -- he impressed, despite not winning any matches, and will lead the club in the Championship this coming season.
Then, finally, there was Ryan Giggs' brief spell as caretaker manager after David Moyes' departure. Various reports suggest the Class of '92 agreed -- quite reasonably -- that Moyes wasn't working out, and launched something of a coup to oust him. Giggs wasn't a realistic candidate to take over full-time, but he's secured an assistant manager role and is now the strong favourite to take over from Louis van Gaal, probably in three or four years' time.
There's a pattern here. Each of these six coaches -- Di Matteo, Dalglish, Sherwood, Monk, Adams and Giggs -- were already at the club when their predecessor was dismissed.
Each of them also had a playing history at the club in question, which meant they probably had more affection among supporters, and more of a core group of support among the staff. Di Matteo had been a Chelsea player for six years, Dalglish was a Liverpool legend, Sherwood was at Spurs for four seasons as a player and five more as a coach. Monk was a Swansea veteran of a decade, Adams is in Norwich's hall of fame for his playing contributions, and Giggs has played for Manchester United more often than anyone.
More intriguingly, each is in a better position after his surprise experience in charge.
This effect means managers must be increasingly careful when they appoint assistants. Paul Lambert's decision to appoint Roy Keane at Aston Villa was highly surprising -- Keane might not have any history at Villa, unlike the aforementioned six, but he quite obviously has managerial ambitions himself.
Lambert has been under constant pressure at Villa, and fans are getting restless. Chairmen are usually reluctant to sack managers because of the financial consequences, but now Lambert doesn't have that in his favour -- it won't cost Villa much to sack him. Keane will surely step up.
On paper, clubs promoting from within is a positive -- encouraging a consistent philosophy despite constant changes. Realistically, however, it's often just the easiest option, and managers would be well advised to surround themselves with those who don't have managerial ambitions of their own.