A top coach or manager is studied down to the minutiae by their competitors and ever bit of extractable information about them, their character, tactics, tendencies and idiosyncrasies into exploits will be explored in ways it's hard to actually fathom. It is not casual analysis, it's obsessive deconstruction that requires so much energy and genius to quell or keep at bay - they get "found out" to the extent that what was previously working has to be rewritten and re-structured just to stay ahead of the chasing pack. Depending on the manager being chased, there is only a finite amount of times they can truly stay ahead of a whole sport trying to catch up with them, so it's not just a case of change and adapt; it's understanding why this is happening and knowing exactly what needs to be done to prevent that from happening. It's basically asking why a chess grandmaster can see 8 moves ahead instead of 6 or 7 as well as considering how much advantage there is in seeing that extra move or two, or having exactly what's needed to remedy any supposed solution to what you're doing.
The best coaches of a particular period have cracked a formula and, within that time period, they rinse it for all it's worth; the best of the best coaches are timeless; they have an innate understanding of the game, which means it cannot evolve past their capabilities as they simply see and understand what is happening and build methods as well as counter measures to whatever the problem presented is. In this case, it's about father time and their own enthusiasm to keep going, rather than them being caught up to. The coaches of an era can actually find themselves being called dinosaurs by the end of their own run - the irony being, they were once the innovator and one to catch, but so wedded to a system or method are they, on top of their own strictures of what is the right/wrong way to play that they can end up being gobbled up by those who either once looked up to them, or simply those who have made it their life's work to best them.
The greatest coaches are dynamic, ahead of the game and always innovating and reinventing things we might even say aren't broken. They are visionaries that lead the game rather than being led by it. They will often cull players or teams and start with a new batch, leaving most scratching their head as to why they've done that, especially if we follow the mantra of it ain't broken, so why is it being fixed? But their understanding and instincts are innate and they see and usher in change via reinvention and iteration #2, #3, #4 and so and so forth. This is manifest in someone like Ferguson having 3 wholly different great sides, with different characters, characteristics, instincts and intent or a Pep constantly throwing out what look like perfectly capable players in favour of something new; he too having numerous iterations and modifications across his teams, none who mirror the other. Michels, the same, and Cruyff. These are the kinds of managers who get bored or old (mostly old); the game never catches up to them, and whatever they were at this or that time is just a vapour because they will not be that 2-3 years down the line, which is why they cannot be boxed in or have single label that fits because what may have been true then, won't necessarily be true when they invariably reinvent themselves again.
