"To stretch the floor" means spreading out the players on a basketball court by positioning them widely apart. This opens up more space for movement and creates better opportunities for scoring and passing. Full definition
He needs to spend the next 6 months working on his 15 - 20 foot game because if he can't stretch the floor he has no chance. (sbnation.com)
He needs a defensive anchor next to him, ideally one who can also stretch the floor. (sbnation.com)
What can you do about someone who has the capability to stretch the floor in an instant without even having to put the ball on the ground? (sbnation.com)