It’s hardly a revelation when a former player backs his old club in some form or another – but it does usually make for a good debating point, especially when it comes to football managers.

“You hear ridiculous things like: ‘Has he lost his magic?’ He won the league 18 months ago, he is one of the most successful managers of all time and he is only young in management terms,” Gary Neville told Sky Sports little more than a week ago.

“Ultimately, let him do his job, let him deliver. There is nothing to suggest he is not going to deliver here yet, in my mind. It is important the club can stick by Jose for three years, let him do the work.”

He is of course talking about 53-year-old Manchester United manager Jose Mourinho, who spent eye-watering amounts of money in the summer – yet just 14 games into the Premier League season his side are already nine points adrift of the top four.

In both seasons under Louis van Gaal, they were sitting pretty in the Champions League places at roughly the same stage in the season.

Regardless of how long it takes Jose to ‘do the work’ – and history says he’s done after two seasons – this isn’t the start anyone at Old Trafford envisaged for him.

What we have seen in the career of Mourinho is a waning influence. From almost a managerial mystic when he burst on the scene, Jose’s abilities to turn a club into an irresistible force have sparked at every club he’s been at before United – yet the sparkler would burn for ever shorter degrees of time.

And in all honesty, the jury is still out over whether the spark will arrive at United at all.

Rather that a football mystic, Mourinho has become Mystic Meg – a parody of himself, starting fires here, there and everywhere without the results to put them out. And whether it’s his tactical nuances, handling of players or his own hunger and experience, it could be his shelf life as a world-class manager is coming to an end.

As much as careers have that shelf life, in English football it’s become increasingly clear managers at clubs have an ever-reducing shelf life too.

By the end of the 2014-15 season, the average tenure of a professional football manager in England was down to 15 months – and well under a year in the Championship. The first half of the following season saw a record number of sackings. Everyone knows what the management game is about.

But perhaps as football clubs try to put more and more layers of continuity and planning in place, there should now be an acceptance that the role of a manager or head coach sits like a team’s kit – you have one for a season, see if you like the results, and then don’t fret because you can try a different style the following year.

Some clubs already do it – Chelsea and Watford being prime examples – and while seeing someone lose their job is never nice, a well-rewarded (they almost always are) 12-month contract coming to an end is not the same scenario.

There will always be buckers of the trend, and there are no issues with that. But the norm has already changed; attitudes should follow.

Alex Neil is still fighting to buck that trend himself – and his side delivered the perfect starter for five against Brentford. He now faces a stern test of his man-management skills in picking his side for Barnsley and keeping his whole squad on board.

He has to decide whether he wants to deal with Barnsley’s threats, or keep faith with the positive signs of those he chose at Carrow Road.

Either way, like any manager, he’s trying to prove he can break the mould and last a longer course.

It’s no wonder they take it all one game at a time.

• Follow Michael Bailey on Twitter @michaeljbailey and Facebook @mbjourno