Estrada (back) was released by the Athletics on Tuesday, Martin Gallegos of MLB.com reports.

Estrada (back) allowed four earned runs on four hits and three walks while striking out three over three innings for Triple-A Las Vegas against Albuquerque on Friday.

Estrada (back) will make his next rehab start with Triple-A Las Vegas on Thursday, the Associated Press reports.

Estrada (back) allowed three earned runs on five hits, a walk and a balk over 2.2 innings in High-A Stockton's loss to Rancho Cucamonga on Friday. He struck out four.