Why not both? Why can't Crowder play a little more 4 and Hayward take some of Smart, Rozier, Green, and Bradley's minutes?
Great players learn to play together, especially versatile players like Crowder and Hayward. Crowder is strong enough to play the Draymond Green role in spurts. Hayward handles the ball well enough to be the primary ball-handler for a lot of the game.
They play the same position, but not the same way. Hayward takes away from Thomas, Smart, and Bradley more than Crowder.