You make a good case but I will have to give the counter, which is fair given I am probably one of the more vocal ones being sceptical of him! I think my major issue with Pellegrini is that he is the wrong fit more than he is a bad manager.
1) I am worried about his age. 63 is old and he does look increasingly jaded in the job. I appreciate not every manager will stay here longer term but I think what we currently need is more of a longer term vision. Had he inherited the side Moyes left I think he would have been perfect for us as he could have tinkered with a disciplined side and given them the little bit they needed to win things. Alternatively hopefully after the next manager comes in say a Koeman, he would be ideal.
However I don't think with his age and the rebuild job we need his age makes him a natural fit. There is little doubt he can manage big ego's but at present that is the least of our worries. I see him as a tinkerer more than a rebuilder.
2) His big game record is very poor in England. Against United he has looked unconvincing. Likewise he has been played off the park and capitulated most games against Liverpool. I can't be doing with that anymore.
3) His style I don't really want to see at Everton nor do I think it will be successful in England. I think they remain quite soft defensively and prone to losing away games. Neither the defensive nor their away frailties have really been tackled by him.
4) Poor signings. Maybe it was above his head but I simply don't think his signings have worked out. The comment you make above that nobody has performed as well as him over the last 3 years. I don't think this is the case really. Nobody has spent as much money as him and 1 league in 3 years, alongside no FA Cup Wins and no trophies in Europe is worse than what his predecessor achieved (and was sacked for). When you spend the sort of money City do you would expect better.
5) Not shown he can bring young players on. There is a lot of criticism for his lack of opportunities for young players who won the FA Youth Cup. I think this should be central to any strategy going forward.
6) Still relies on predecessors key names. Despite spending huge sums of money City are still very dependant on Kompany, Toure, Aguero, Silva & to an extent Hart. He has spent lots of money and not rectified this.
My worry is he will be like Walter Smith was with us. Won a lot of trophies but used to being able to outspend his opponents. I don't get inspired listening to him. I'm not saying he's a bad manager but just not right for what we need currently. I do also think there has to be a bit of realism. Often the people slagging off De Boer for his record are rather uncritical of Pellegrini's. Relative to others in their league they have received similar backing. De Boer has always been in the top 2 and won the league 4 in 6. Pellegrini has won 1 in 3.