Pep Guardiola is heading to the Etihad in the summer, but many feel Manchester City should not have made the announcement mid-season.
The Citizens have got their act together of late, but a dismal run from the beginning of February to the end of March ended their title challenge as they took just four points from six games.
The decision to announce the Bayern Munich boss as the new manager came on February 1, and Pellegrini blames the timing of the announcement for crucial losses.
"In the start of February came the news about the change of the manager, telling the players I will not continue here next year," he said. "A lot of things that involve the minds of all the players."
The Chilean pin-pointed two vital games that he feels have cost them dearly:
"For different reasons, we lost important games in February against Leicester and Tottenham. For me, they're the two games that don't allow us now to be involved in the title."
Luckily for City, they have managed to play to a high standard in the Champions League and face Real Madrid at the end of the month in the semi-final of Europe's premier competition.
A key factor in their recent resurgence is the return of their mercurial Belgian Kevin De Bruyne. He has been fantastic in City's last few games, scoring in both legs against Paris Saint-Germain and in the Premier league against Bournemouth.
With Yaya Toure back in the side, and Vincent Kompany nearing a return from injury, City fans will be hoping they can finish the season in style, both on the continent and domestically.