From the Guardian:
Managers dream of honours but they are almost all fighting a losing battle for survival. Time is shorter than ever and they now last only 1.7 years on average in their posts. The odds against them emerge in the most extensive inquiry into their profession that has ever been conducted.
Dr Sue Bridgewater, of Warwick Business School, found that there were 678 managerial changes in England's four divisions between August 1992 and December 2005. Of that number, 536 were openly declared as sackings and they involved 360 different people, some of them dismissed more than once.
The rate of attrition is on the increase. At the start of the period studied by Bridgewater a manager would typically have 2.7 years to prove himself in a job.
Crystal Palace have been the most fevered club of all, with a dozen changes since 1992. That year is a suitable base point because it saw the inauguration of the Premiership with all its radical consequences. The human impact of many clubs' desperation has been grave. Almost half of the greenhorn managers removed from their first job have failed to return to football at that level.
The career carnage has driven the League Managers Association to campaign for the Football League to imitate the Premiership, where managers must have a pro licence - although there is an exemption until 2010 for long-serving characters such as Sir Alex Ferguson. The LMA hopes to persuade the remaining 72 clubs to demand a fixed level of qualification.
"Once you've proved that this kind of preparation works, the people who make the decisions over who they employ will include it in their thinking," said the LMA chief executive John Barnwell. Bridgewater shows that managers with a pro licence win 37% of their matches: those with no qualifications or just a B licence win only 30% of the time.
Sackings are most frequent at the lower levels and 23 managers were ejected in the old Third Division in the 2001/02 season alone. Those who do endure may not get much further. Of the Premiership's members only Everton, with David Moyes, and Portsmouth, in the anomalous case of Harry Redknapp, appointed a manager from a lower-division club. Sam Allardyce, Alan Curbishley, Alan Pardew, Mick McCarthy and Paul Jewell had to achieve promotion to join, or rejoin, the elite.