Gary Neville is now learning a hard lesson and one which will have major consequences for his life after Valencia.
Put bluntly, he has turned a silk purse into a particularly ugly sow's ear and seriously damaged his credibility.
First and foremost, his reputation as an up-and-coming young coach is in shreds.
His position with England must be under threat now or at least, should be in doubt since he wasn't able to turn up for their training camp this week and cannot do the job properly.
He spent several days explaining to the local media in Valencia that he would have no problem heading off to England for the training camp but had to do a u-turn.
That's both jobs in trouble and in my opinion, the one he was best at, punditry, is also seriously threatened by his decision to dip his toe into management.
Put it this way, if he's back doing analysis for Sky next season or even turns up on our screens during the Euro 2016 finals, how can anyone believe what he says?
His vision for Valencia didn't work very well and that's the only evidence we will have to judge him on.
As a pundit, he must judge everyone but can he pontificate about other managers or players in these circumstances? I don't believe he can.
I have to laugh, Neville is the man who absolutely tore into Arsene Wenger and described him as 'naive or arrogant'.
Talk about the pot and the kettle!
I accept that Neville was somehow swept up in a wave of popular support for his Sky work and probably thought he was master of the universe.
I'm sure he had many people egging him on and telling him to grab Valencia with both hands which was fair enough. But they should have told him to let go of England first and make a real commitment.
Football will very quickly drop a custard pie on anyone who gets ahead of himself and that's what Valencia has been all about.
Neville was delusional to think that he could do two jobs at once.
Long before that, he should never have been doing pundit's work which required him to talk about players he was meeting on the training ground during England camps.
Don't for one second think that players didn't notice what Neville was saying on a weekly basis.
There are no more sensitive souls than professional footballers and any criticism he offered would be remember and stored away.
We have a good example of how double-jobbing is rarely a good idea in football with Roy Keane.
He took a position at Aston Villa supporting Paul Lambert and after some time trying to serve two masters, he realised that both were suffering so he cut his ties and reduced his workload to Ireland and Ireland alone.
And he was just an assistant, supporting two managers.
I have some form in this area myself. I was part-time Ireland boss when I was manager at West Brom but the FAI went into that with their eyes open.
I told them that I didn't feel I would be able to devote the kind of time and energy needed to manage an international team but those were different times and we were trying to do the best we could in the circumstances.
It's much better now of course and we will never need a part-time boss again but I knew even then that it was impossible to do both to the best out your ability.
This whole saga has also painted Roy Hodgson in a poor light and his employers. This kind of thing could only happen in England where politics play as big a role in the international team manager's job as the football.
If I was Hodgson, I would never have agreed to Neville splitting his time between Sky and England and the idea that he could be the manager of such a big Spanish club and still have some role to play in preparing for the Euro 2016 finals is just ridiculous.
In terms of ability, Neville has shown very little as a manager and I wonder did he seek the advice of Alex Ferguson before he decided to take over one of the top clubs in European football as a project.
Ferguson always tipped Ryan Giggs as a natural for management and I can't remember him mentioning either of the Neville brothers in that context.
Oddly enough, Giggs's credibility has grown by sitting beside Louis van Gaal in a dignified and patient way, showing the kind of loyalty and commitment that I like to see in staff and managers.
He never struck me as management material one way or the other. He's a man of few words and he only ever lit up in public on a football pitch where he really did shine brightly.
But you never really know until someone gets a chance and Ferguson is not a bad judge to have in your corner.
Giggs may have to leave Old Trafford to progress but I'll venture that we won't see Neville follow the apprentice route.
In fact, I don't think we will see him take any route other than straight back to the comfort of the Sky studios.
Sky are not stupid people though and I wonder how they will react when they see that Neville's standing as the voice of football analysis doesn't carry the same authority?