Yes there is upside. SD is not that unkind to RH hitters (SD has just never had one worth mentioning, not that Bradley is "power" hitter but still). He is capapble of reaching double digit HRs and SBs w/ ~280+ average.
quoting Tristan Cockcroft @ ESPN
Something else to consider: Bradley, who has a history of attitude problems, was a .282 hitter with seven homers and 25 RBIs in his first 50 games for the Dodgers, and a .280-8-28 hitter in his first 50 games for the Athletics, which indicates that he often gets off to a hot start for a new team.