My two cents on Tevez, knowing him since his debut, I was at the field...
On contrair to what many think, Tevez it's not a level below Rooney, nor he was just a workhorse, nor he never before played as the main man in a team (he did it in Corinthians in an excellent way and close to that role in Boca).
Tevez went to United accepting being loaned and not bought.
He accepeted to play second fiddle to Rooney and CR (he respected the already established major figures), in such style, he therefore played with more focus on intensity and pressing than his best atributes.
At doing so, United found one of the more cohesive frontlines ever, to this day Rooney says Tevez was his best partner, precisly because both could interchange and played each others role while pressing like mad men.
Tevez in such situation, should have been instantly bought.
Yet...
It didn't happen, Fergie played the card of trying to diminish his stature to in consequence play less money for him, in the meantime he even bought Berva that perhaps was more akin to him as a player. So Tevez read that situation as not being respected and he doesn't care if he is Fergie, Lennon, Ghandi or whomever, he always was that way, he comes from very very rough origins to care about that when he feels he it's not respected. This last thing of how Fergie tried to lower his price and took to long to offer him a contract, it's even to this day support from Rooney, Rio, Evra and cia. There are several situations in tevez carreer that today his mates support his view, but Tevez being Tevez in the day didn't even bothered to clarify or protest (like Mancini's bench affair).
All in all, he still it's Tevez, it doesn't warrant that he wouldn't anyway one day get bored and leave the Club, or clash with fergie or whomever, but at that point in his carreer, he certainly lower his profile, his expectations, his style of play and demands in the field and he didn't received what HE thought was deserving.
Between all this stuff, he was managed by crooks and like I've said he still is Tevez, so even if Fergie didn't tried that approach, he might have done sthg. else in time that would have end with him out of United.
That whole situation is the reason why United didn't had Corinthians, Juve, City one man army Tevez version for at least some period.
Remarking this last thing, because Tevez being Tevez left Boca in a rush while being loved, the same in Corinthians and even in Juve where he did almost everything right (from training, fitness, perfomances, leadership) he left saying he was heading Boca and ended in China...Carlitos way.
The sad thing it's that United still won after these "three amigos", but also was pretty obvious that Fergie was in the peak of his powers and that he was starting to shift that United tradition of flair and steel to sthg different and even if at first with Berva and Persie he still got lots of talent, the soul was starting to be left aside.
He even started to have problems with Rooney because of him questioning the course of United after the trio was dismantle.
I absolutely get Tevez being hate as hell. But this hatred must not coverred that he was a lot better player than many give credit for and that even all those shyte situations regarding United, the banner, the RIP and such also showed the character of the fella perfoming even better under such pressure.
He even ended being the catalyst that made City believe and get bigger, at periods he even did such thing within City with his coach against him and the squad demanding Mancini to call him back to win the title, the motherfecker always did what he wanted, he didn't had finesse, but he was a hell of a player in terms of abilty and personality. It could have been sthg if United could kept those three for many seasons, a pitty, a real pitty.