I'm not sure effort is the problem quite as much as tactics is, but one thing I will add is that it doesn't help for the players' morale to hear comments from Jose questioning the quality of the squad, and the need to spend more money. It's just not good on an individual level, but collectively too.
I've no doubt someone will counter with that players shouldn't be so delicate and that they get paid obscene amounts, but the thing is, I completely agree with that. I'm not justifying their behaviour, if they are putting less than maximal effort in. In my opinion, if nothing else then you should at least play to your max for the fans who pay their money and give up their time to come and watch. Instead I'm making an observation as to what I believe to the case. It's not something I'd want to hear from my boss, but unlike the players I'd have little choice but to get on with it and improve. The players are spoilt, we all know that.
Again, in the event they're not trying their best then this is the 3rd manager in a row that it's happened to, as the OP alludes to. If enough players turn then it's only going to end one way for Jose and seeing as it's far easier to replace a manager than a squad, we all know what that outcome would be. Jose is the one who has to make the changes, but I fear he is too stuck in his ways to do so. If it's just a handful of players then I guess we just need to show patience as Jose weeds them out. It's hard to tell though from an outsiders perspective.