I don't know. They won't count against the limit until the ACL season starts and most of the releases haven't been guys who would be displaced by DSL players outside of maybe one low-A pitcher if Wande Torres skips the ACL.
I think it has more to do with the fact that, between pitchers with options likely to start in AAA and guys on minor league rosters, they have 73 pitchers in full season ball right now, not even counting college pitchers who didn't make their full-season debut last year but certainly are on track for a full-season spots or guys the Brewers will inevitably sign as minor league free agents. That makes it tough on a guy like Brailin Rodriguez, who would have been entering his final year before minor league free agency likely starting at high-A
The Campbell one was the most surprising to me, even with the Brewers not exactly treating him like a prospect last season, because the Brewers' only real position of depth at AAA right now is first base, presuming neither Martinez nor Clarke get plucked in the Rule 5 draft.