The veteran goalkeeper has rediscovered his best form under coach Paolo Vanoli and played a key role in the Viola's move away from the Serie A relegation zone.
De Gea told La Gazzetta dello Sport: "New players have arrived who have given us energy, but the coach's great work must be emphasised. We were dead, it was a desperate situation, and Vanoli brought us back to life.
"And (new sports director Fabio) Paratici is very present: he loves talking to us and following our training sessions. He's doing a great job. I also thank general manager (Alessandro) Ferrari, the club, and (sporting director Roberto) Goretti, who have been supportive."
On taking over the captaincy from Luca Ranieri, De Gea continued: "Vanoli spoke with Luca and I, and told me that, being the oldest, he expected a lot.
"I was ready; I had already been captain at Manchester United. I have an excellent relationship with Ranieri; he's very important to the team. He's one of the captains."
Fiorentina will meet Crystal Palace in the Europa Conference League quarterfinals and De Gea added: "Winning a trophy would be amazing for the fans; we can do it."
Regarding the future, he's clear: "I have two years left on my contract and I'm happy here, but now's not the time to think about the future. I want to save Fiorentina and give my best in the Conference."