2006-07: Sebastian Stefaniszin really shone during the 2007 World Juniors for Team Germany. He kept his team competitive throughout the tournament, going 2-3 with a .909 save percentage and a 2.81 goals against average; however in the end, Germany was relegated. Of particular note was Stefaniszin's play against Team USA in the tournament's opening match, where he stopped 38 shots in a 2-1 overtime victory.
Meanwhile, Stefaniszin has seen very little time in the DEL, playing in just two games in the 2006-07 season for the Berlin Polar Bears, with a goals-against average of 4.60 and a save percentage of .769. He spent the majority of the 2006-07 year with the Polar Bears junior team, seeing action in 36 games and producing a GAA of 3.88.
2008-09: Stefaniszin is in his first full year in the DEL, after working his way up from the junior and then farm teams. With the Iserlohn Roosters, he has a .903 save percentage and 3.34 GAA in 23 games, sharing time with veteran Norm Maracle.
2009-10: Played in both the DEL and the 2.GBun leagues. For Iserlohn of the DEL, he posted a 2-9 record, a 4.06 GAA, and .882 save percentage. For the Landshut Cannibals of the 2.GBun, he posted a 3-2 record and 1.97 GAA.
2010-11: Stefaniszin appeared in 8 games for the Nurnberg Ice Tigers in Germany's DEL as a back-up to one-time San Jose prospect Patrick Ehelechner. Stefaniszin was 2-3 and had a 4.48 GAA and .865 save percentage for the tenth-place Ice Tigers. In four games with Landshut in the second division he was 1-3 with a 5.39 GAA.
A dual citizen of Germany and Austria, Stefaniszen was signed by the Vienna Capitals of the Austrian League to back up former St. Louis Blues goaltender Reinhard Divis in 2011-12. There is little likelihood that Stefaniszin ever plays in North America.