He isnt a rebuild manager and that wasnt what you brought him in for. But plans change, and hes gonna have to be a rebuild manager. LvG had the right idea, but it wasnt executed well. Even as an "instant success" manager, I feel Mourinho could do a better job at rebuilding than LvG could.
As for how poor Mourinho has been. In terms of instant success? Cant say yet, but after the games we've seen, this is not how everyone envisiged your season starting. After 3/4 games I think this season, when everything seemed fine and dandy, I was saying how you're guranteed for the title. As were a lot of people, you were sitting pretty near the top.
But I really do think its just fans having to re-adjust their expectation, before a ball was kicked the names of Pogba and Zlatan and Mhik were driving fans to believe that you would win the title straight away. Well.... now you know thats not gonna happen (probably), and the process of lowering the bar is not something that is easily done. Its a process filled with hesitance "should I lower it? Should I leave it? If I leave it i may not hit he target, but then if i lower it isnt that kinda like cheating? Since im making it easier for myself" Its a process filled with anger, since you feel like you shouldnt even be in this situation to begin with.
Thats my opinion anyway, I think had Jose come in and said its going to be a long process, this season Im aiming for top four but really I just want to cement my style of football. Then fans would have more paitience. But he didnt. He came in and it seemed like he was gonna blow the league apart and return the glory days within in a blink of an eye.