PHOENIX -- This isn't what the A's envisioned.A three-game sweep at the hands of the D-backs was not supposed to follow a big series win over the Rangers that saw Oakland score a combined 18 runs and take three of four from baseball's powerhouse. Yet, another loss at Chase Field on Sunday, a 4-3 decision, led to just that, as the A's dropped to a season-high nine games under .500. "Not a good series," Bob Melvin said. "That was a bad series. Whenever we get swept, it's a bad series." The A's skipper, visibly disappointed, didn't offer much else. His team's play, it seemed, said enough, particularly in a poorly executed first inning. Arizona was quick to the board against lefty Travis Blackley, tallying three runs in the frame. All could have been avoided, though, if not for an error committed by shortstop Cliff Pennington. With one out and the bases loaded for Jason Kubel, Blackley induced a ground ball from the outfielder that second baseman Jemile Weeks fielded cleanly at second base. With a double play in mind, Weeks made a throw that Pennington missed completely, allowing a run to score and keeping the inning alive.