In the May 15 deal, the A's acquired Blanks and sent minor league outfielder Jake Goebbert to San Diego.
Herrera was 3-4 with a 3.38 ERA in nine starts with Class A Beloit. The 19-year-old Venezuelan pitcher was 12-12 with a 3.36 ERA in 39 games, including 33 starts, in three seasons in the A's farm system.
Copyright 2014 by The Associated Press
This story is from ESPN.com's automated news wire. Wire index