Saponara left the Viola on Friday's deadline day.
“It's always easy to fall into the usual cliché in these situations, but I have to leave a message for all those who are writing to me this weekend," wrote Saponara on Instagram.
“This 18-month journey didn't meet expectations that we all set, I didn't put in the performances that the club had invested in me for and this makes me very sad.
“I leave behind the sadness and disappointment at not taking this great opportunity the way I should've done."
Saponara also referenced the passing of Davide Astori.
“Despite all of that, a bolt from the blue marked a new beginning for the season and lives of all Fiorentina fans, including me, involuntarily creating a strong bond between us players and the reality around us. As far as I am concerned, that bond is unbreakable.
“This city taught me a great deal, it made me a man, but in particular gave me something precious and rare: the recognition of who I really am, in all my strengths and weaknesses.
“Thank you to Tommy and all the Golden View for literally adopting me. Thank you to Drino for the pizzas in his garage with beer and Champions League games on the TV, thanks to Vale for the coffee at the bar, to Alessio, Akram, Mariuccia, Cesare and I could go on forever.
“Basically, thanks to everyone who even with a brief chat helped me feel at HOME. A new adventure begins for me, sending me towards a new place and new experiences. Florence will always remain with me."