Before I say what I'm going to say, this is not directed at you in particular but is more of a criticism of what is prevailing point-of-view around the league, especially in the media.
The PL has disappeared so far up it's own asshole with the notion that it's special and that things that work abroad won't work here and that players who are "proven" in the league have special value.
With few exceptions, all of whom are members in what has become a clear "top 6", PL teams are fucking lazy. They make the same lazy managerial appointments, spend all their money on the same lazy player types, and justify it all by saying that other things just won't work in the PL. In reality, they're just afraid to try some different, which I find amusing because they have no shame about wasting their TV money -- which makes them richer than pretty much every club in the world -- on players and managers that plainly aren't worth it. I'd rather us fail trying to be more efficient than fail doing the same old crap.
There's a real chance for us to get ahead of the rest of the league (outside the top 6) by doing some different and doing it effectively. But instead, we're tending towards the same old lazy bullshit. It's a ceiling we impose on ourselves.
I know what you're saying, but I think it does differ from other leagues, because of the strength of teams at the lower end of the table. Most of the big european leagues are more top heavy and while it's more common on continent, you can get away with carrying more potential than ability, you can play more younger players and rotate more.
I'd say the more stupid thing is the old English mentality of kick it out when in any doubt, or not giving youth support and time to develop. As a fanbase we were scared shitless of Unsworth coming through as a youth manager, yet that happens at top end of La Liga and across Bundesliga over last decade and a bit, where most of the success has been.
DoF is more a trendy thing to curb the worst excesses of managers and focus on development, but a great manager would be better without one. There are virtually no big clubs in Europe, where the DoF has more authority than manager and very few that appoint managers with any success. And very few of the best coaches would work in those roles, as you'll take the fall like Koeman did.
There are plenty of teams on the continent who have a DoF who doesn't have control of managers, they just do recruitment like a head scout but with more authority on recruitment. At that point I really don't care what title they have, call them the supreme footballing sensei if you fancy.