Complex sentence: Head coach Steve Kerr missed the first 43 regular season games because of a back injury; assistant coach Luke Walton served as interim head coach during Kerr's absence, and he led the Warriors to a 39--4 start.
Split into simpler sentences: Head coach Steve Kerr missed the first 43 regular season games because of a back injury. Assistant coach Luke Walton served as interim head coach during Kerr's absence and he led the Warriors to a 39--4 start.