ステート・カレッジ・スパイクス
Gregerson was drafted by the St. Louis Cardinals in the 28th round of the 2006 MLB draft out of Saint Xavier University. He spent his first professional season between the Rookie-Level Johnson City Cardinals and the Short-Season State College Spikes in 2006. He went 0–1 with a 3.86 ERA in 15 games with Johnson City and 6–1 with a 1.72 ERA in 12 games with State College.