Why do managers decline and not dominate forever?

It's the same with any intellectual field. It takes a special mind to introduce a new idea or a concept... and most of the time that one huge breakthrough (that often happens relatively early) becomes the pinnacle of their career. There are exceptions even in that already elite group of, well, geniuses, that keep producing new ideas year after year, decade after decade... but they are even rarer. Just like in football — you can probably count those on the palm of your hand: Ferguson, Ancelotti (both of whom are more adaptable that necessarily ground-breaking), Guardiola... probably Cruyff, Michels, Lobanovsky, but that's where it already becomes questionable. And then there are those who make one huge breakthrough before slowly fading out as the game's development passes them by — Sacchi, van Gaal, Mourinho etc.

Plus with football there's also psychology in play. To keep developing you have to constantly question yourself... but you also need to produce that aura of confidence about your own ideas so that your own players fully commit and don't start second-guessing your decisions. And it's easier to simply buy into your own once very much deserved hype... which works to a point before you suddenly become a parody of yourself — with Mourinho being the most notable example. Yet if you question yourself too much and keep experimenting, on the one hand you're more open to innovations and are safer in the long run... but on the other one you become prone to overthinking stuff — which is the most common criticism of Guardiola in his post-Barca CL campaigns.
 
Generally speaking.. The older you become
- you lose the ability to (quickly) adapt to a changing environment.
- you get more out of touch with the generation of players.
- your lose your speech abilities and therefore will have more problems getting your points across.
I'll also add that they have slower reflexes hence not being able to move pointers on the tactics board and players get the wrong idea of the tactics.
 
The managers of the well run clubs tend to stay as long as they can. Guardiola won't find a better structure in football for him to succeed, so he stays. Same for Klopp and Liverpool until recently when there seems to have been a slight shuffle behind the scenes there. Potter made a big mistake leaving Brighton for the circus at Chelsea. There's no end in sight for Howe at Newcastle.

Then the managers like Tuchel are forced to choose environments that aren't ideal to them. Give him the city job and he's be considered the best manager in the world after 2 years and probably stay long term. (assuming they get away from the 115 meeting unscathed as expected)
 
The managers of the well run clubs tend to stay as long as they can. Guardiola won't find a better structure in football for him to succeed, so he stays. Same for Klopp and Liverpool until recently when there seems to have been a slight shuffle behind the scenes there. Potter made a big mistake leaving Brighton for the circus at Chelsea. There's no end in sight for Howe at Newcastle.

Then the managers like Tuchel are forced to choose environments that aren't ideal to them. Give him the city job and he's be considered the best manager in the world after 2 years and probably stay long term. (assuming they get away from the 115 meeting unscathed as expected)
This is why club popularity among managers has changed. Even the big clubs, if not run well, don't attract.
 
Cruyff obviously had a brilliant footballing mind, but I don't think he should be mentioned in the context of managers that continually innovated tactically and/or rode through the trends of different eras successfully, never letting the game obviously pass them by.

He wasn't a manager for too long, and while not so rigidly wedded to one formation as Sacchi was (probably the most one one-dimensional of the consensus great managers imo), he did have a consistent philosophy and way of playing with Ajax and Barca. This didn't change that much, which is arguably why three of those titles right after his dominant first went down to the final day and were reliant on Real Madrid/Depor blowing their advantage. Then when the fine margins turned, including being humiliated in the CL final after trying to turn the pre-match psychology into a war of footballing ideology (swashbuckling, proactive Barca vs negative anti-football Milan), he was out of the game within a few seasons.

Could he have come back from the CL final humiliation and the last few seasons at Barca? I'd imagine so, yet it's far from certain, and he decided that path wasn't for him.
You’re conflating the volatility of the man, and his ability to start a fight in an empty room with his footballing genius, I feel. The football principles are so sound that they are valid to this day, but Cruyff’s ability/ propensity to have once-allies turn on him is as legendary as he is, so you simply must separate the two as it is Cruyff letting Cruyff down that is likely to be the trigger point, not the flaws in what he’s actually presenting.
 
Usually old managers complain about “you can’t be tough with these new kids, they are sensitive blabla” case in point Mourinho. So usually its a communication problem with newer generations.
 
Meh, Cruyff's coaching career lasted what, a decade? And it didn't end on a high note, either. If anything he's an example of how personality and human qualities are so much more important than tactical understanding or ingenuity
 
You can understand with players that as they get older they wont be as good their younger self. A 25 year old Messi was better than a 35 year old Messi, A 25 year old Ronaldo was better than a 35 year old Ronaldo.

But why do managers decline? They have no excuse right? Mourinho for example, he's definitely not as good was he was back in 2004-2010 but why not? I mean if anything he should just as good if not better with all his experience and knowledge he now has. Wenger, Capello, Van Gaal, Benitez, you could go on, they all declined. Why couldn't they be as a good they were back in the 90s/00s?

What is it down to? Not adapting to modern day tactics? Their style of management 20-25 years ago not working in the current age? I'm sure they're all clever enough to change and adapt.

It can be different. Example: Jupp Heynckes...
 
You’re conflating the volatility of the man, and his ability to start a fight in an empty room with his footballing genius, I feel. The football principles are so sound that they are valid to this day, but Cruyff’s ability/ propensity to have once-allies turn on him is as legendary as he is, so you simply must separate the two as it is Cruyff letting Cruyff down that is likely to be the trigger point, not the flaws in what he’s actually presenting.

It's not that I don't rate the footballing principles and tactics he displayed as a manager, or can't see how his Barca team was an influence on more recent greats like Guardiola. As I say, I think he probably could have come back to success again with another club. It's that he literally didn't do some of the things being credited to him, that longer-lasting managerial greats like Ferguson, Ancelotti did. He had a short managerial career and retired rather than show that he was personally capable of navigating through different periods as a manager while still staying on top of changing tactical trends or continue to personally innovate.
 
It’s more that the game is so media driven and perfectly good managers get thrown on the trash heap.
 
The prevalent style of football changes every decade or so. Managers have to adapt or they quickly find themselves at the back of the pack.

Today's Tiki-taka High Pressing era will probably come to an end one day too.
A team at the Euros had great success beating the press by using the long ball. Worked beautifully and surely some will not be so ideologically driven that they will embrace that approach.

West Ham had good success under Moyes by being much more direct than most teams in the league.
 
It's a talent and reputation profession requiring results and most run out of last chances.
 
You can understand with players that as they get older they wont be as good their younger self. A 25 year old Messi was better than a 35 year old Messi, A 25 year old Ronaldo was better than a 35 year old Ronaldo.

But why do managers decline? They have no excuse right? Mourinho for example, he's definitely not as good was he was back in 2004-2010 but why not? I mean if anything he should just as good if not better with all his experience and knowledge he now has. Wenger, Capello, Van Gaal, Benitez, you could go on, they all declined. Why couldn't they be as a good they were back in the 90s/00s?

What is it down to? Not adapting to modern day tactics? Their style of management 20-25 years ago not working in the current age? I'm sure they're all clever enough to change and adapt.
A number of factors, probably.

First of all, the fact that they are not playing does not mean that the job is not taxing. It requires an awful lot of work that becomes harder to accomplish as you age.

It is also very stressful, because you are reliant on other people to do what you need to get done, and you don't have the same direct agency that players have - they always think they can directly affect a game whereas managers are stuck on the sidelines wishing and hoping.

The stress element is evidenced by the number of managers that have had major heart problems. When you get to a certain age, who wants that? Much better to do some nice easy media or whatever.

Also, only the very best can adapt to the inevitable changes in football styles, cultures, philosophies, tactics etc. When Ferguson retired some 10 years ago, football was completely unrecognisable from what it was when he took over in the mid 80s. Like night a day. And football now is very different from 10 years ago. You need to be special to keep up with such massive evolutionary changes.

Further, in relation to the above, a lot of managers, even some great ones, are one-trick ponies. Once their schtick gets figured out and countered, they have no plan B, and so slide down to lower and lower levels, or exit the game completely.
 
Football changes over time, and while many have short bursts with new ideas, staying ahead of the curve and constantly adapting for your ideas to be at the top is rare. It's not just 1 idea works and keep using that idea, teams will adapt to it and they might only work with certain individuals. You need to keep changing.
 
Evolution of tactics + most of their msg comes around being manipulative to young players around the dressing room which gets spoiled eventually.