Wassermann played collegiately for the Samford Bulldogs. Signed as an undrafted free agent in 2003, Wassermann posted a 2.34 ERA over five minor league seasons. He was a Birmingham Baron in 2005 and 2006. He started the 2007 season with the triple-A Charlotte Knights. He was promoted to the White Sox in July 2007, and after going 1-1 with a 2.74 ERA in 33 games, solidified a spot in the bullpen.