First reported on Twitter by A's beat writer Susan Slusser, the A's have freed up a 25-man roster spot for second baseman Mark Ellis by demoting first baseman Daric Barton to Triple-A Sacramento. Barton was one of the best first baseman in the American League last season despite a major lack of power, but hasn't remotely come close to repeating those numbers this season.
The current expectation is for former Diamondback Conor Jackson, who's played primary the outfield for Oakland this year, to take most of Barton's plate appearances over at first. The 29-year-old hasn't been all that different from Barton, providing walks but little power and a low BABIP, but his .263/.353/.325 line is still an upgrade from him.
With Barton, a good deal of his decline can be attributed to a punchless bat and a decline in BABIP. His .131 isolated power from 2010 was poor, but this season's .055 mark is utterly acceptable for any hitter, especially a first baseman. He still walked in 14% of the time, leading to a decent OBP, but overall he's been a below-replacement player this season according to FanGraphs.
A strong performance at Triple-A should allow him to return later in the season, considering that Jackson isn't a long-term replacement, Barton is only 25, and the other primary alternative, Chris Carter, is striking out 38% of the time with Sacramento.