There have always been patterns in systems in football. Some come into and go out of fashion depending on what way the most successful teams of the moment are playing. What has changed is managers wanting players to stick to those patterns and less individualism in the game.Up until 15 years ago, I would have agreed with you, but football has become a game of patterns and systems, with little room left for improvising. Old-school managers like Clough, Ferguson or Keegan would have no place in today's football, unfortunately. To be successful as a manager, you no longer need to know your players, think outside the box and devise a strategy according to your squad. You need to be able to implement an efficient system.
If your players can't adapt to different systems and/or managers then, quite simply, they're not good enough, regardless of their ability with a football.
That's what we're about to find out. Some people still think our squad should at least have us in midtable but the players couldn't/wouldn't adapt to Frank, they couldn't adapt to Tudor and unless something changes very quickly, they'll be playing in the Championship next season. They're not bad players per se, but they just don't fit into any system: they can't play three at the back, they can't play a very attacking game, they can't adapt to the opposition... well, we are where we are for a reason.
As for the managers, maybe I'm wrong but I think my explanation still beats 'he's incompetent', 'he's an idiot', 'he's a dinosaur' or 'he's trying to get us relegated on purpose' - arguments I've read many times over the years.
You still need to know your players and how they fit into a system. I'd say knowing your players is even more important now on a personal level as modern players need more handholding. Ferguson would adapt to any era, he was a master at motivation and ensuring that he had the correct people around him.
They adapted to Frank, it's just the system he had them playing lacked any creativity beyond putting a cross in. They won't adapt to Tudor if he keeps constantly playing players out of position doing roles they don't have the ability for.