The PSG star, formerly of Barca, took the award after inspiring the club to a Quadruple last season, which included the Champions League and Ligue Une titles.
Xavi told Foot Mercato: "Ousmane is an exceptional player, that was clear to us from the moment he arrived in Barcelona . We recognized his full potential and did a lot to make him feel comfortable and happy.
"We saw a player with great potential for development, who was truly eager to learn, and he developed enormously with us."
He also said: "Then the offer came from Paris St. Germain, he went to Paris, and that's where he fully developed. He's happy there; he feels like a star of the team, of the project.
"And on top of that, they won the Champions League, where he shone with many goals and assists. He made the difference."