The first? Jered Weaver in 2006.
One bit difference between them? Weaver entered that season as a first-round draft pick and one of the game's better pitching prospects (No. 21 that spring, according to John Sickels). Griffin was a 13th-round pick, and entered this season as the 13th-best prospect in the Athletics organization. Last season in Double-A, he went 2-3 with a 6.47 ERA.
Nobody saw this coming.