Barton played sparingly during spring training, and was retroactively placed on the DL on March 24 with a strained shoulder. He returned to action with triple-A Sacramento, and hit a grand slam Sunday. Allen was the A's Opening Day first baseman, but has gone hitless in seven at-bats, with five strikeouts.
Barton played well for the A's in 2010, posting a .393 on-base percentage, but his shoulder injury limited his playing time and his production in 2011. Meanwhile, Allen's got impressive numbers in the minors but has batted .205/.291/.375 in the majors, and he's probably running out of chances.
With Allen gone, Barton figures to get most of the time at first base, though Kila Ka'aihue is still hanging around. There's not a platoon there, as both bat left-handed. Considering Barton's good glove at first base, Ka'aihue probably slides into a DH platoon with Jonny Gomes or some other nondescript right-handed hitter.
Allen probably takes Barton's spot with Sacramento, but only if he gets through waivers. We'll see if one of the other 29 teams is looking for a 4-A first baseman who can't hit the curveball.