His departure from the active roster set off a series of roster moves, with the A's also optioning left-hander Daniel Coulombe to Triple-A Nashville on Monday and promoting right-hander Andrew Triggs and lefty Patrick Schuster.
Schuster is pitching with his fifth organization but only now readying to make his big league debut. The 25-year-old, a 13th-round Draft pick by the D-backs in 2009, was named to the Pacific Coast League All-Star team last week. He's been superb for the Sounds, pitching to a 1.30 ERA in 34 2/3 innings with 37 strikeouts.
"Just trying to stay consistent, throw strikes and keep a positive attitude no matter the situation I was coming in," Schuster said. "Just tried to stay level-headed, not try to get down when other guys were getting called up."
Opponents were hitting just .206 against the left-hander, who impressed as a non-roster invitee in big league camp this year.
"This guy really kind of came out of nowhere in spring," Melvin said. "We knew a little bit about him, but we knew a lot more about him in Spring Training based on his performance. We started out matching him up against some lefties and then running him through for a whole inning. He pitched really well for us, and he goes down and, basically, the entire season has been pitching pretty well.
"Another great story. Really persevered. Tip your hat to him, a lot of credit for a guy that keeps grinding at it, has a great year at the right time."
Schuster arrived in Minneapolis on Monday ahead of the A's series opener with the Twins having gotten only a couple of hours of sleep after learning of his callup. His parents, Roger and Sharon, flew in from Tampa for the game, and his grandparents and girlfriend, Lea, will also be in attendance.
Oakland has already used 22 pitchers this season, including position players Josh Phegley and Tyler Ladendorf.
"We've gone through more pitchers in half a season than I can ever remember, both in the rotation and now the bullpen," Melvin said. "That's why our organization creates the kind of depth that they do."
To make room on the 40-man roster for Schuster, the A's recalled outfielder Andrew Lambo and placed him on the 60-day disabled list, as he recovers from surgery for testicular cancer.