Garcia replaced Zdenek Zemen in the Italian capital and matched the best start in Serie A history when his side beat Napoli to record their eighth win in as many games.
Roma started last season well but faded in the second half of the campaign to finish sixth in Serie A, before going on to lose the Coppa Italia final to arch-rivals Lazio.
With the departure of key players during the close season – including Erik Lamela, Marquinhos and Maarten Stekelenburg – Garcia had some rebuilding to do and Balzaretti revealed the Frenchman's positive attitude during pre-season gave Roma the belief they needed.
"Garcia did very well in pre-season training to do a certain type of work with us, which laid the foundations for these victories," Balzaretti told a club members' videochat.
"He convinced some players to stay and since he arrived we all believe in this group.
"In football there’s little to invent, so he does simple things and puts them into practice.
"Now it is gratifying to put our training routines on to the pitch, as well as making the club, fans and ourselves happy. We are all Roma."
Balzaretti has started seven games this season and scored once - in the Rome derby when he broke the deadlock against Lazio.
