The midfielder made the move to Fiorentina on an 18-month loan with obligation to buy for a reported €10m.
“Saponara gave us very little on the field this season, less than he could've done," Corsi told Radio Marte.
“He grew up in our family and was always considered a member of the side. Then the player asked to be sold when an offer from an important club came in, so we had to react accordingly.
“I think Fiorentina made an investment for the future. We didn't want to sell him over the summer and his performances really dropped off after that. Up until last January he was playing like a champion.
“Napoli asked me for him 18 months ago, the offer was nearly €20m, but we weren't ready to sell him too. The same happened over the summer, when we had already lost Lorenzo Tonelli, Mario Rui, Leandro Paredes and Piotr Zielinski.
“This time it went differently, as we were able to pick up Omar El Kaddouri, a trequartista we like very much."