The magic of resizing down to 1600 on the long end!
Here is a larger view, but again not 100%, you can then gauge any voodoo from larger samples.
Also, I cannot stress the need for prioritizing shutter speed more than ISO... As you can see in that image, there is a sweat drop in the lower left that still shows movement, so 1/2000th for these guys still aren't enough. The younger the players, the lower you might be able to go with shutter, but always experiment. I suspect you will find that higher ISO images (if processed well) with faster shutter will yield better results overall than lower ISO with slower shutter.