While Atchison was not spectacular by any means in 2010, it was a fairly obvious move to bring him back. Providing decent middle-inning relief, Atchison comes incredibly cheap and is, if nothing else, dependably average. The Sox have a pretty empty bullpen, so every non-disaster arm counts.
Atchison returned to the United States after two years in Japan to bring his daughter closer to the doctors she needed to treat a bone condition she was born with. The Red Sox picked him up as a free agent, allowing him a chance to earn a spot in the bullpen out of Spring Training.