When people take offense to the idea that Poch was a success here that's very much what is being said.
I don't think anyone ( least of all me) thinks Poch Mk1 wasn't a success here. That was prime Poch who, whether by luck or design, managed to put together a thrilling, young, hungry team playing wonderful high tempo attractive attacking football.
However, there was regrettably also a Poch MK2. This Poch unfortunately did the following:
1. Write a macaronic book about players still here and espousing a quite ridiculous philosophy including the reason why he thought players would be shamed by being substituted!
2. Presided over a shambolic transfer policy - £320m plus spent on largely wasters since July ? 2016. 27 players bought in his regime - and his coaching failed to develop them. Record buys included Sanchez, Sissoko and NDombele. Failed to refresh our first team by being too loyal to too many players for too long. Had zero succession planning - to allow both Walker and Tripper to be sold without adequate replacements and allowed our only plan B ( Llorente) to go without signing a replacement. Bought a succession of wide players without addressing our core needs.
3. As a supposed great coach, he never developed any of our promising youth academy (with the possible exception of Winks) and allowed many promising youngsters to leave.
4. He made some simply crazy remarks ( e.g. regarding lemons) - and his comment about leaving if we won the CL was stupidly timed and may we'll have cost us the game. Starting an unfit Kane in that game was also a palpable mistake.
5. For the whole of his last year we played dire football and it was virtual relegation form - we failed to win away for almost a year iirc.
6. Finally, he never actually won anything - and indeed has never won anything as a coach. He seemed to believe the FACup and League Cup were beneath him. He couldn't deliver a winning mentality and lost virtually all our crucial games
Poch Mk2 was a disaster and we certainly needed a change. Whether Mourinho is the right man remains to be seen. But I am not prepared to write him off yet until at least the end of next season when we see the direction of travel and he has had adequate opportunity to show us what he might be able to achieve.