Athletics outfielder Bobby Kielty needs arthroscopic surgery on his left knee and will be sidelined for three-to-six weeks. Kielty, who came to camp in the best shape of his career, injured the knee Sunday during a rundown drill -- and just when he was ready to get through a healthy spring training, for a change. "It's definitely a bummer," Kielty said Wednesday. "Right now I could play on it, but we're deciding that the best thing is to make sure it's good for the season."