Here's a couple ways of looking at it...
The Brewers currently have 70 Wins.
The six pitchers in the rotation - Freddy, Quintana, Priester, Woodruff, Henderson and Misio - have a combined team record of 56 W - 23 L (.709 W%) in their outings.
If they keep that pace up for the rest of the year that would be another 34 wins.
Or, going back to the April calendar flip the Brewers have played to a .636 W% after losing their first four games. Play to that pace the rest of the year and it would be another 30 or 31 wins.