Ross, 25, was a second-round draft pick of Oakland back in 2008. The right-hander has a 6-18 record and 5.33 ERA over 148 2/3 innings with the Athletics. He's made 53 appearances over his big league career, including 21 starts.
It's unclear whether the Padres plan to use Ross as a starter or out of the pen, but Petco Park has been a great place for pitchers to reemerge. Of course, that could change some with the fences moving in for 2013.
Oakland also sent A.J. Kirby-Jones to San Diego. The first baseman is 24-years-old and hasn't played above High-A, but he did post a .843 OPS and 21 home runs last season.
In return, Oakland received utility man Andy Parrino and reliever Andrew Werner. Parrino has played in 79 games for the Padres over the past two seasons, positing a .200/.319/.256 slash line while playing shortstop, second base, third base, right field and left field.
Werner made it to the majors last season after being signed out of the Independent Leagues by San Diego in 2010. The left-hander had a 5.58 ERA over eight starts with San Diego and a 3.70 ERA over 22 minor league starts in 2012.