Leon will pitch in relief for the A's, John Hickey of the Bay Area News Group reports. Leon worked as a starter with Triple-A Nashville and was an option to fill the open spot in Oakland's rotation, but that is expected to go to Kendall Graveman. Expect Leon to pitch in middle-to-long relief for the A's.

Leon was recalled from Triple-A Nashville on Wednesday. Leon was called up to take the roster spot of Drew Pomeranz (shoulder), who was placed on the disabled list. Leon will likely be available out of the bullpen right away, but he started for Nashville, so he will at least be a candidate to start next time Pomeranz's place in the rotation comes up.

Leon was optioned back to Triple-A Nashville on Thursday, the Bay Area News Group's John Hickey reports. He was only up with the A's for one game, and he allowed an earned run on two hits and a walk in Wednesday's contest. Chris Bassitt was called up to replace him in the A's bullpen.

Leon was called up to the majors Wednesday, Susan Slusser of the San Francisco Chronicle reports. Leon has struggled through his first two starts with Triple-A Nashville this season as he's allowed seven runs and 11 hits in just 8.1 innings pitched, but he'll join the big league team to provide added depth to the bullpen. The Athletics' pitchers have been heavily taxed of late, so his big league stint may only last as long as it takes other relievers to get rested.

Leon was optioned to Triple-A Nashville on Sunday, reports Jane Lee of MLB.com. After a rough 2014 where Leon posted a 4.97 ERA, he came into spring with very little chance to make the team. This will be his third year as a full-time starter and he will need to show some progress limiting base runners in 2015.

Athletics optioned RHP Arnold Leon to Triple-A Sacramento. Leon was up for Wednesday's doubleheader but didn't appear in either game. He returns to a 4.34 ERA with 22 strikeouts over 29 innings at Triple-A.

Athletics recalled RHP Arnold Leon from Triple-A Sacramento. Leon will serve as the 26th man during Wednesday's doubleheader, providing some length out of the bullpen if needed. He's posted a 4.34 ERA with 22 strikeouts over 29 innings at Triple-A Sacramento this season and will make making his major league debut when he gets into a game.

Athletics pitching prospect Arnold Leon will make his major league debut during Wednesday's doubleheader against the Mariners. He gets the call over Josh Lindblom. Leon, 25, has posted a 4.34 ERA with 22 strikeouts over 29 innings at Triple-A Sacramento. He'll be sent back down after the spot start and is not worth streaming in fantasy leagues.

Athletics optioned RHP Arnold Leon to Triple-A Sacramento. Leon appeared in just three Cactus League games for the A's and was, of course, in the center of Mexico's brawl with Canada in the WBC. He'll get a shot with the big club at some point this season.