The 26-year-old Keller made his major league debut last Aug. 4 and pitched in 10 games for the Marlins, posting a 3.38 ERA with 11 strikeouts. He excelled with Triple-A New Orleans, holding opponents to a .217 batting average with a rate of 12.2 strikeouts per nine innings, 10th-best in the Pacific Coast League.
The Angels signed the 19-year-old Estrada as an international free agent one year ago. He played in the Dominican Summer League.
The Angels also designated reliever Jake Jewell for assignment. The right-hander has a 6.99 ERA in 21 appearances with the Angels over the past two seasons.