The Chicago Cubs have traded starting pitchers Jeff Samardzija and Jason Hammel to the Oakland Athletics for 2012 first-round pick Addison Russell, 2013 first-round pick Billy McKinney, pitcher Dan Straily and a player to be named later, the Cubs announced Saturday.

Samardzija, 29, is 2-7 with a 2.83 ERA this season. Hammel, 31, is 7-5 with a 2.98 ERA after his latest win, earlier Friday against the Washington Nationals.

Hammel is set to become a free agent after this season, while Samardzija has one more year of arbitration before becoming a free agent.

Russell, 20, is ranked third among all prospects on ESPN Insider Keith Law's top 100 list. He plays shortstop, the same position occupied by current Cub Starlin Castro and top Cubs prospect Javier Baez. Russell has appeared in only 18 games this season due to a hamstring strain, hitting .333 in 58 at-bats at Double-A Midland. Current Cubs Triple-A hitting coach Brian Harper was on the staff of the Mesa Solar Sox of the Arizona Fall League last year when Russell was a member of the team.

McKinney, 19, has a .241 batting average with 10 home runs and 33 RBIs in 75 games for Class A Stockton this year.

Straily, 25, is 1-2 with a 4.93 ERA in seven starts for the A's. The right-hander is 13-11 in 41 starts for Oakland over the past three seasons.

Samardzija was drafted by the Cubs in the fifth round in 2006 and worked his way up from reliever to starter. He put together his best two months of his career in April (2.38 ERA) and May (1.38 ERA) but got little run support or bullpen help, leading to his 2-7 record. However, in June, his ERA was 5.45 as he went 1-3.

The Cubs and Samardzija had been talking on and off for two seasons about a contract extension but never got close to inking a deal. Samardzija wants to be paid full market value, although he's still a year and a half from free agency. The Cubs reportedly offered him a 5-year, $85 million deal that he rejected.