Complex sentence: In recent decades, Polynesians--in particular Samoans--have found great success in the NFL, so much so that the island of American Samoa has been referred to as "Football Island" by outsiders.
Split into simpler sentences: In recent decades, Polynesians--in particular Samoans--have found great success in the NFL. So much so that the island of American Samoa has been referred to as "Football Island" by outsiders.