The Yankees added a fresh arm to their bullpen Saturday, purchasing Dave Robertson?s contract from Triple-A Scranton/Wilkes-Barre. The club also optioned Kei Igawa back to Triple-A, one day after he was called up, as reported by the Associated Press. In other news, the team acknowledged that Hideki Matsui could need surgery on his ailing left knee if it doesn?t start feeling better. The slugger was placed on the 15-day disabled list Friday.