In case you forgot about Carl Lawson..

[Sled21]

There's a simple answer to this...… field turf. While the turf is more forgiving when you fall on it, the big disadvantage is that when you cut and change direction on it, or someone goes into your knee, the cleats are much more likely to hold than they would on grass. It makes it great for runners to cut, but puts more stress on the knees as a result. And when someone goes into your leg and your foot can't move, you're going to lost a knee.....