Complex sentence: The left-footed Schaars is a versatile player who can play either as a defensive midfielder or as a left-sided midfielder and has grown into being one of the most important players for AZ being captain of the team on many occasions.
Split into simpler sentences: The left-footed Schaars is a versatile player who can play either as a defensive midfielder or as a left-sided midfielder. He has grown into being one of the most important players for AZ, being captain of the team on many occasions.