The Brewers should trade from their pitching but not from anyone on the major league roster or even the 40 man roster. While the Brewers have a bunch of starters, many have issues that may need another starter available to cover.
Peralta-OK
Woodford-Coming off injury and has already had some set backs while rehabbing
Cortes-Coming off injury and may never really be healthy anytime soon
Quintana-He is 36, velocity is already down form last year and any dead arm period would be a killer.
Patrick-Innings limit
Henderson-Innings limit
Misiorowski-innings limit
Priester-OK
Myers-OK
There are just so many ways in which the Brewers could end up short on starters. Given they have a bunch of guys with options it doesn't make sense to move anyone.
Now there are a bunch of pitchers that could be moved: Letson, Yoho (if they aren't going to give him any innings in MLB not sure what the next steps are), Wichrowski, Crow, Meccage, Hardin, (Gasser probably isn't health enough right now). I am sure that list contains someone's favorite pitcher in the Brewer system, but these guys should be available and more replaceable given the Brewer's ability to produce pitchers.