Actually, regarding LVG, one thing that was clear was what he was trying to achieve . He wanted us to retain possession, move the ball rapidly searching for an opening and take advantage of this opening when opposition players get moved around because of our ball movement.
Now, he was not able to achieve it, because this system obviously required highly skilled technical players and we had Schneiderlin, Rooney and a past it Schweinsteiger and also because LVG proved quite inept in the transfer market in getting the players he needed to implement his methods. He was more in the Wenger mould, where playing a certain way was more important to him than actual results.
With Mourinho, we have much better record of winning matches and he does set up to not lose. Our results are much better, but his system does not seem to encourage ball playing skills, and even after 2 years we are stuck at just getting past the next match with a favourable result and hoping we reach the next transfer window.
With LVG, we could see Rashford, Lingard and Martial clearly develop an understanding and improve, and we felt excited for next season. We were thinking about what levels they would achieve rather than which shiny new talent we would purchase to end our problems. The system actually encouraged them to play well and why wouldn't it because not matter what, he still emphasized doing things with the ball rather than off it. With Mourinho, we are still stuck at, "if he gets his players next season". I mean, we already have Pogba, Martial, Lukaku, Sanchez. Pogba has been here for two years. I don't see any noticeable improvement in them.
If we mess up in the transfer market, then we are again doomed for another season, because I don't see a whole lot in the present system which encourages our players to reach new levels.
I think, like LVG, Mourinho will have to be replaced (not immediately), but the only thing we will have with us is a excellent set of core players waiting to be taken to the next level. The next manager will have to start from scratch, trying to instill a definite method of play.