Hayes, 22, was drafted in the 8th round of the 2006 draft. Last season he pitched primarily for the Bowling Green Hot Rods, putting up a 3.53 ERA over 43.1 innings. In his 5-year career with the Rays organization he had a 4.03 ERA in 295 innings.
Oliveros, 25, struggled to a 6.10 ERA between Charlotte and Montgomery last season.
Fields, 25, was our 44th round pick in the 2004 draft. Last season, primarily with Montgomery, he hit only .219, but did knock out 15 homers in 347 ABs.
Wiegand, 23, was drafted in the 25th round of the 2009 draft. As Bowling Green's primary firstbaseman last season he put up a .250/.339/.374 line.
Folli, 25, hit .174/.269/.246 for Montgomery after coming over from the Cardinals in an August trade.
Contreras, 23, put up a .250/.311/.415 line in 200 ABs for the Princeton Rays in 2010.