Bonucci was in Milan last season joining from Juve, before returning on loan, in a deal that say Caldara and Higuain join Milan.
The centre back captained Milan in his single season at the club and Suso believes his absence will be felt.
“Yes, we lose leadership and experience,” Suso told Marca of Bonucci’s departure.
“He brought many things in a very young team. He feels he took a step back signing for Milan and that is why he returns to Juventus.
“When the project is interesting and players like Higuain arrive it is always positive. The level of the team increases.
“If the year is good for him, it will automatically be good for us too. He is a player who stands out well and knows what to do with the ball.”