Complex sentence: The pick and roll is often employed by a shorter guard handling the ball and a taller forward or center setting the screen: if the taller defender switches to guard the ballhandler, then the offensive team can have favorable mismatches.
Split into simpler sentences: The pick and roll is often employed by a shorter guard handling the ball and a taller forward or center setting the screen. The purpose is that if the taller defender switches to guard the ballhandler, then the offensive team can have favorable mismatches.