Just ask John Greig and Billy McNeill.
Both men are heroes to the Rangers and Celtic support respectively due to their feats, domestically and in Europe, in the 1960s and 1970s.
Yet, when they stepped into the dugout, their tenures ended in disappointment, failure and, ultimately, the sack.
Greig was unfortunate in that he took charge at a time when investment in the squad was practically non-existent.
Rangers had embarked on a major redevelopment of their stadium in the wake of the Ibrox Disaster in 1971, and matters on the park suffered badly as a consequence.
McNeill enjoyed his fair share of successes in his two spells as Celtic manager – not least a historic league-and-cup double in the centenary season of 1988.
And his inability to win the title after that was more due to negligence at boardroom level – which, just a few years later, took the club to the brink of extinction – than any failing as a coach on his part.
Still, his services, and those of his great friend and rival Greig, were eventually dispensed with.
Having now spent more than 20 years at Rangers, as a player, coach and now manager, Ally McCoist is acutely aware of the harsh realities of the world he inhabits.
The former Ibrox hitman knows he will live and die by how his team performs.
He understands the affection he is held in as the greatest goalscorer in Rangers' history will not spare him the sack if form dips and results dry up.
He is cognisant of the fact that his handling of the ordeal the Glasgow club went through last year will, while greatly appreciated by supporters, not keep him in employment if his side fails.
He is well aware that, despite them being well clear at the summit of the Irn-Bru Third Division and certain to win the title, losses like the one his team suffered at the hands of Annan Athletic at the weekend are unacceptable.
However, knowing what is required of you is one thing. As Greig and McNeill found to their cost. Meeting those demands and surviving, is another.
That McCoist's position has come under scrutiny in the last few days in the aftermath of 2-1 defeat to part-time rivals says much about the difficulty of his role.
Yes, the weekend result was an enormous embarrassment. But a team he was forced to cobble together in a matter of weeks last summer is, despite the loss to the Galabank minnows, still 17 points in front.
The ultimate objective for the 2012/13 campaign, to win promotion and start the move back up the leagues, will be achieved comfortably.
He has been operating under a transfer embargo imposed by the SFA for the non-payment of taxes during the ill-fated reign of former owner Craig Whyte.
He has been unable to strengthen his squad. He will need to rely on bringing in free agents in order to do so this summer. Whether he can do so to any great degree without spending any money remains to be seen.
But irrespective of the unusual position Rangers have found themselves in this term, fans still have very high expectations.
Exiting the Ramsdens Cup, Scottish Communities League Cup and William Hill Scottish Cup to Queen of the South, Inverness Caledonian Thistle and Dundee United respectively, has rankled their followers greatly.
For all the obstacles Rangers have been asked to overcome this term, they still boast the second highest wage bill in Scotland. Only that of Celtic is higher.
They were still able to field six current or ex-internationalists at the weekend – Neil Alexander, Ian Black, Andy Little, Dean Shiels, Lee McCulloch and Lee Wallace.
The paucity of their defence against tiny Annan was deeply disturbing for their supporters. The scoreline flattered them. They could, and should, have lost by more.
It was not an isolated incident either. They have been woeful at home in draws against Elgin City and Montrose and against Stirling Albion away, where they also suffered a 1-0 defeat earlier in the season.
The players are certainly culpable. But so is the man who is charged with training them, selecting them and motivating them.
The comfortable lead they have in the Third Division may have caused some to switch off. But they should still be able to beat these teams easily.
McCoist's first season in charge was beset by off-field troubles. It was no great surprise Rangers were beaten to the SPL title by Celtic after being plunged into administration last term.
The players took substantial pay cuts to preserve the jobs of non-playing staff and uncertainty shrouded their futures.
Yet, before all that Rangers had crashed out of four cup competitions – the Champions League, Europa League, the League Cup and the Scottish Cup.
McCoist was responsible for many memorable cup successes before he succeeded Walter Smith. He was allowed to take charge in those tournaments.
But he needs to lift silverware as a manager in his own right to convince Rangers fans he is the right man to lead them.
The chances are that, given all he has been through, McCoist will be given time.
But his team needs to play at a far higher level and on a more consistent basis if he is to be as successful as a manager as he was as a player.