The A's and Cubs announced the big trade on Saturday, with Jeff Samardzija and Jason Hammel heading to the West Coast for a package of prospects that included the A's first-round selections in each of the past two drafts.

The A's began the day with the best record in baseball, but GM Billy Beane felt he needed to add depth to a rotation that has already responded well to season-ending injuries.

"We had to dig into our depth really early, and we felt like we needed two (starting pitchers)," Beane said.