The Oakland Athletics placed starting pitcher Marco Estrada on the Injured List with a lumbar strain on Wednesday. Chris Bassitt was recalled from Triple-A to take Estrada's place on the active roster. (Susan Slusser on Twitter)
Estrada has a history of back issues and just allowed 13 earned runs over his last 7 1/3 innings pitched, so it's possible that he has been attempting to pitch through an injury. He allowed five earned runs over his first 16 1/3 innings before his recent outings.