It's the players, not the manager.
Our players, especially in defence, are shit.
Look at how great Baily is compared to the rest of them, and he is by no means the end product! No one would've regarded him as one of the best defender around and yet he is miles ahead of the rest of our defence.
Smalling shits himself every time in a big match. Mentally fragile. He cannot handle one on ones. Same with Blind, who shouldn't even be a defender but our alternatives are even worse than him. Valencia works hard, quick, strong but will never be a real defender. Shaw is still raw and last season sets him further back. And sadly, the rest of them is even worse!
We have not had proper top quality defenders for 3 years.
It's why LVG was fixated on keeping the ball. Because we would concede quickly if we didn't.
It's also why Mourinho plays extremely negatively against top teams. Because he has to. Most top quality attacker just dribble past Blind and Smalling. Look at Hazard and even Konte. So he has to compensate with numbers and hope someone make a block in, or intercept the pass.
It's all well and good saying we should be attacking, Jose should make an instant impact but there is only so much he can do in one window. He bought one starter for the defence, and now he's trying to work out a system that works against the best teams.
Against the lesser teams, we've been entertaining. Far better than anything we've witnessed since SAF left. We battered Leicester, we battered Stoke but luck wasn't on our side. Even against City, we started poorly (again, poor defensive errors) but if the ref didn't bottle it, it might've been different. We did ok at Anfield.
So yes, we got smashed by Chelsea but most of those are individual mistakes. Surely Jose's game plan didn't involve a collective brain fart for the first, nor Smalling turning his back on the ball to let it sit up for Cahill.
It is way too early to say he's done.
And those saying Chelsea last season, let's not forget he was replaced by another highly experienced manager, and they still didn't make it to any European competition. It wasn't all Jose.