Ronaldo left Juventus to join Manchester United towards the end of the summer transfer window and left the Italian giants with little time to bring in a replacement for him.
The veteran forward scored 101 times in 134 appearances for Juventus during his three-year stay at the club and won Serie A twice.
After barely finishing fourth in the league last season, Juventus have fallen off a cliff this term and are currently seven points behind the Champions League spots.
Calderon stressed that Juventus still cannot be taken lightly this season but conceded that Ronaldo’s departure has adversely affected them despite talk of the club being happy to shed his wages off their books.
He indicated that apart from the Portuguese’s goals, Juventus are also missing the competitive spirit he brings inside a dressing room with his constant drive.
Calderon told Italian outlet Tutto Mercato: “Juventus are not at their best but they are always a team to take into consideration.
“Undoubtedly, Cristiano’s exit did not favour them.
“Cristiano is a player who gives a lot to the teams who he plays for and not only in terms of the goals he scores.
“But also with his competitive spirit that infects his team-mates.”
Ronaldo has scored six times in the Premier League this season and his goals have also powered Manchester United to the last 16 of the Champions League.