5. Bill Castro
Years as a Brewer: 1974-1980
411 IP, 3.56 FIP, 1.27 WHIP
Bill Castro was drafted by the Milwaukee Brewers and went on to have a successful career out of the bullpen. The Dominican Republic product posted six quality years with the organization. While he was never named to an All-Star team he was a model of consistency throughout his time with the Brewers.
Apart from a rough season in 1977, Castro could always be counted on in the Brewers bullpen. Castro returned to Milwaukee in 1992 to serve as the bullpen coach up until his firing in 2009. He was one of the longest tenured coaches in Brewers history.