Complex sentence: Swiryn temporarily retired at the end of 2011-12 Top 14 season due to persistent injuries, but returned to playing rugby and made the U.S. National rugby sevens team in 2015.
Split into simpler sentences: Swiryn temporarily retired at the end of 2011-12 Top 14 season due to persistent injuries. He later returned to playing rugby, however, and made the U.S. national rugby sevens team in 2015.