Mancini was dismissed at the end of last season after a dismal defence of the Premier League title and a shock defeat to Wigan in the FA Cup final. He also failed to take City out of the group stages of the Champions League.
Former Real Madrid, Villarreal and Malaga coach Pellegrini was appointed in his place and has enjoyed unprecedented success after a slow start, even talking up a desire to win four trophies this season, as reported by Sky Sports.
But in an interview with BBC Sport, Mancini disputed Pellegrini's role in the club's current form and is quoted saying:
I'm happy that Manchester City is one of the best teams in England because I built this team.
The players that score the goals are players that I bought—Sergio Aguero, Edin Dzeko, Yaya Toure, David Silva and Samir Nasri.
Mancini's claim is valid in the respect that the likes of Sergio Aguero, Edin Dzeko, Yaya Toure and David Silva have all played large roles in the club's progression this season.
However, the Guardian's Daniel Harris points out on Twitter that there are a lot of players responsible for City's current form who were not signed by Mancini:
Signings made after Pellegrini's departure, such as Alvaro Negredo and Jesus Navas, have added strength in depth and experience that didn't exist during Mancini's reign.
Negredo has taken no time to adjust to English football and is the club's top scorer this season with 23 goals, per BBC Sport. Navas, meanwhile, has also fitted seamlessly into the squad, scoring four goals and assisting another six in his first 20 appearances, per ESPN FC.
Pellegrini's management style has united the squad, while Mancini notoriously rowed with a number of high-profile players and staff at the club, causing a tense atmosphere, per Ian Ladyman of the Daily Mail Online.
The Chilean has also, impressively, guided the club to the knockout stage of the Champions League for the first time in their history and booked them a trip to Wembley in the Capital One Cup final.
Mancini began putting the foundations in place for City to enjoy a long period of success, but he only took the club so far. Pellegrini has proven this season that he is the right man to continue the club's development and take them on to new levels that they haven't reached before.