The Oakland Athletics have reported that starting pitcher Daulton Jefferies (shoulder) underwent thoracic outlet surgery this past Monday. The operation was performed by Dr. Greg Pearl in Dallas, Texas. The plan is for Jefferies to be shut down from throwing for four months. After that, he’ll do some brief throwing, then he’ll be shut down again until Christmas when he’ll begin an offseason throwing program. The 26-year-old made eight starts this year and went 1-7 with a 5.72 ERA and a 1.37 WHIP.