I primarily agree with the op. I see or would hope to see our system slightly change. Whilst I agree with the 'ain't broke don't fix' theory, I'm not 100% sure what we were watching was working perfectly. Lets not forget whilst Tevez is performing as one of the best strikers in world football, we are still only 3rd and score less than United or Arsenal.
I know we only saw 25 minutes of the City Valencia pre season, but it very much looked like Mancini fancied a front 1 with 2 behind. Vs Valencia it was Ade up top, Tevez and Silva with freedom to play. I guess Mancini is looking to replicate this with Dzeko up top, Silva and Tevez with freedom to roam.
I feel with Tevez as the focal point of attack and his willing to track back to get the ball it leaves us very short of a fulcrum for an attack.
I would guess or hope with a 4-1-2-2-1 that the fullbacks would provide width, Silva a link between all play, Dzeko a fulcrum for attacks, and a much needed aerial threat, maybe Tevez would not flourish to the extent he is doing now, but the team may score more goals.
I would hope that if this system were to work, and I have faith in Mancini to make it work City as a team will be better off. Hopefully Dzeko and Tevez will both be around the 20 goal mark, with Silva adding 5-10 and a good contribution from Balotelli when he plays, as apposed to being almost solely reliant on Tevez's goals.
If we were top and dominating the league I would have stuck with what were doing, but lets face it, Villa was not the first game in which we have struggled against the parked bus, maybe this system maybe in time will prove more affective against the parked bus.
If we only look at the swamp, last year Rooney scored 30+ goals and United won nothing, this year, Rooney is not as important yet they remain unbeaten and look like walking the league, favouring team play over Rooney's individual talents.