The A's acquired outfielder Casper Wells from the Blue Jays in exchange for cash considerations on Monday.
To open a spot on the 40-man roster, the A's transferred Scott Sizemore (left knee) to the 60-day disabled list, and a corresponding move for the 25-man roster will be made once Wells joins the team in Boston.
Wells spent the spring with the Mariners, for whom he hit .189 with two home runs and 14 RBIs in 16 games before being designated for assignment on March 31. He was then claimed off waivers by the Blue Jays on April 10, and he did not appear in a game before again being designated for assignment on April 15.
Wells spent most of last year also with Seattle, hitting .228 with 10 homers and 36 RBIs in 93 games. Forty-two of his starts were in left field, 23 were in right field and nine were in center. He led the team with eight outfield assists and did not commit an error in 159 chances.
Sizemore was placed on the 15-day DL on April 10 with a sprained left knee. An MRI revealed a torn ACL, and Sizemore underwent successful surgery on April 16. He also missed the entire 2012 season after tearing the same ligament in the same knee on Feb. 27 of last year.