Complex sentence: The team was 4--0 during the pre-season, and during the regular season, their 11 victories was the third best in franchise history, and the Seahawks went undefeated at home for the third time in franchise history after 2003 and 2005.
Split into simpler sentences: The team was 4--0 during the preseason, and during the regular season, their 11 victories was the third best in franchise history. The Seahawks went undefeated at home for the third time in franchise history, after 2003 and 2005.