The Milwaukee Brewers were still in the American League when Gary Sheffield was playing for them, so there is no danger of having him top a third list in a row. The Brewer who has put up the best OPS in 100 at-bats or more is Ryan Braun, who clocks in at .331/.402/.645. (That’s a 1.047 OPS!) At the opposite end of the spectrum is J.J. Hardy, who from 2005 to 2009 had an .751 OPS, but only managed a .554 OPS against the Giants during that time. The Brewer with the greatest difference between his OPS against the league and his OPS against the Giants is second baseman Ronnie Belliard, who hit .317/.385/.500 against the Giants in 104 at-bats from 1999 to 2002, while hitting .263/.341/.396 generally as a Brewer in that time. That’s a difference of .148.
The list can be found here.