Complex sentence: The WSHL was previously affiliated with USA Hockey from 1994--2011 but changed its affiliation to the AAU in 2011 primarily because of restrictive USA Hockey rules governing the number of import players.
Split into simpler sentences: The WSHL was previously affiliated with USA Hockey from 1994--2011. The league changed its affiliation in 2011 primarily because of restrictive USA Hockey rules governing the number of import players.