I’ve watched a few interviews with him and various players who played under him and it seems to me that he can only coach a certain type of player. The kind of player he can push and abuse a bit and get a reaction.
I get the impression that Drogba, Lampard, Terry, Carvalho etc. were these kind of players which is why they were great for him and having that much of a team working for him means players in between will probably fall in line, so his spending of money is somewhat justified if he feels he needs to bring in some of his style players to do what he does (the same with Pep bringing in his style of player) but I think it says a lot about his man management that he can appear to fail so badly with other players. He’s clearly tried to get reactions from the likes of Shaw, Mkhitaryan, Martial and even called them out as basically weak in public and it’s gone the other way.