The Cardinals acquired right-hander John Lackey from Boston just before the trade deadline to bolster their rotation. They open a series Friday against NL Central-leading Milwaukee on Friday in St. Louis.
Miller (8-8) held San Diego to two runs and three hits in six innings, struck out five and walked none. He earned his first win since June 7.
St. Louis roughed up San Diego rookie Odrisamer Despaigne a day after playing what manager Mike Matheny called the team's ugliest loss of the season, a 12-1 defeat Wednesday night.