Bergman wanted to 're-theatricalize' Molière. Serving as Dom Juan's foil, sganarelle sometimes enacted Dom Juan's seductive desires while his master remained a vicarious voyeur.

Two important elements have been presented in most of Bergman's staging of Molière: first, an often brutal unmasking of human foibles; and, second, a farcical, stylized playfulness exposing the silliness of the characters but also revealing the production's reliance on slapstick and commedia dell'arte.
But the reviewers were bewildered by Bergman's approach. Was it a character study or a theatrical farce? 'It seems that Bergman has not been able to decide which Dom Juan he would stage' (Rolf May). Not much was left of the traditional portrayal of Molière's Dom Juan as a demonic iconoclast; instead, the production was, said one reviewer: 'A play about male fantasies and male angst that only knows love as possession and booty'. (kr, Bayrische Staattszeitung)

When Bergman's production opened in Munich three months later, the critical reception was much more positive. One reviewer wondered if a difference in performance could simply be attributed by the weather (armin Eichholz). Or could perhaps the stage be partly responsible? The Salzburg Landestheater had been a new performance area for Bergman and his all-Munich ensemble.

References 

Birgitta Steene, Ingmar Bergman: A reference guide
(Amsterdam University Press, 2005)