The move means the A's are without an extra infielder, though Adam Rosales is expected to join the club soon barring any setbacks in his rehab assignment with Triple-A Sacramento following nearly six months of nursing his surgically-repaired right foot back to health.
"I was surprised," LaRoche said. "I didn't see it coming, but with Rosales coming off the disabled list, they were going to have to make a decision quick. With the game yesterday, they needed an extra pitcher, so I guess they can do all right for a couple of games without an extra infielder until Rosales comes back."
LaRoche, 27, was batting .247 with five RBIs in 40 games. He started 28 games at four different positions, including 17 at third base, after beating out Eric Sogard for the utility job out in Spring Training.
The A's, who now have an open spot on the 40-man roster, have 10 days to either place LaRoche on waivers, trade or release him.
"Obviously there were a lot of things that I could have done better," he said, "but I was happy with the opportunity to get to play all of the positions. I got a lot more playing time than I was expecting. Now I'll just see if another team out there needs me.
"I would obviously prefer to be in the big leagues, and if that's not here, hopefully it's with another team. If there's not that need, then I'll probably be in [Triple-A] Sacramento."
For the time being, manager Bob Geren said Kevin Kouzmanoff would play at shortstop or second base in the event Cliff Pennington or Mark Ellis was unavailable, and Conor Jackson could fill Kouzmanoff's place at third base.
"Obviously we needed the pitching today," Geren said. "Andy played all the positions and did a fine job of what we asked him to do."