According to Corrigan, the Argentinian joined City in a €45 million (£38.8 million) move in 2011, but Los Rojiblancos had hoped for at least €15 million (£12.9 million) more for the player they'd signed from Independiente for €22 million (£19 million) five years earlier.
Corrigan added that "the saga dragged on for two months amid a widespread feeling that the player had tried to force through a move to crosstown rivals Real Madrid."
Aguero arrived at the Vicente Calderon aged 18, and he scored 102 goals for the club in 233 appearances before switching Madrid for Manchester.
The Sky Blues have reaped the rewards of his transfer ever since, per Squawka Football:
The striker has been a key player and established himself as one of the world's best centre-forwards, and he was instrumental in City's two Premier League titles.
However, his future at the Etihad Stadium is no longer certain after the arrival and immediate impact of Gabriel Jesus, which saw Aguero start City's last two games on the bench.
Indeed, he isn't certain of it himself:
Goal's Sam Lee believes the 28-year-old could be on his way this summer:
While there are few forwards in the world who can match Aguero for quality or ruthlessness in front of goal, City boss Pep Guardiola may not feel he's a natural fit for his plans if he's not linking up with team-mates or taking part in passing moves the way he wants.
The Spaniard has been prepared to let go of world-class players for the same reason in the past, such as Samuel Eto'o and Ronaldinho at Barcelona, so it's not out of the question.
If Aguero leaves, it appears he won't be welcomed back to Atletico with open arms.
The club have seen several other similarly talented frontmen leave in recent years, such as Fernando Torres, Radamel Falcao and Diego Costa, but unlike the trio, the terms on which Aguero left evidently angered Cerezo, and they've not been forgotten.