Tevez's return has seen City spark back into life.
Asked if the season would have turned out differently were it not for his dispute with the Argentina striker, Mancini said: "It's normal that if you have another player like Carlos you can score more goals.
"The difference is clear but we did everything in November and December to try to keep Carlos here.
"We have good players and Carlos is one of them. In the end we'll decide."