sports shooting

How do you guys shoot sports? Do you use selected focus points on the ground where the athletes are running, or on the body? How do you weigh in the importance of DoF, noise, and freezing the action?

I did some casual sports shooting and when the sun started to go down, so I slowed my shutter speed to a minimum of 1/500, and opened up my aperture. I had a 70-200/2.8, so my DoF got pretty shallow, and I was trying out the focus point on the ground in the same plane as the athletes, but as you know the focus points are a lot wider than the indicators would... indicate. With everything in the AF point being similar (unlike when on a body) I found that it focused on the closest part of the grass / bottom area of the AF point, a bit in front of the atheletes, leaving them not as sharp as I would like.

Of course I could practice having the center of the AF point slightly behind the plane of players, or have it on the body, but just wanted to know what you folks do.

I was borrowing the lens, so I did not calibrate it with my camera to see any back/front focus issues with my DSLR, which could've been it.