What good point guards do

A good, true point guard makes the sum of the parts greater than the whole. He just makes the whole team work better. A good point will deliver the ball the right player at the right time at the right spot on the court in order for the shot to happen. Players who get the ball under those circumstances ought to shoot a lot better than those who do not. I wonder how much better a team's overall shooting percentage improves with the presence of a good, true point guard.