Nikon D100 - What are the best settings for night youth football game action shots?

My Lens is: AF-S NIKKOR 70-200mm 1:2.8GII ED.

Currently, my pictures are either out-of-focus, too dark, or too light.

When I use a high ISO in shutter priority mode, the pictures are too dark. When I lower the shutter speed, the pictures are too blurry.

The D100 goes up to ISO 1600, which isn't much by today's standards. If you're already opened the aperture as wide as possible (the camera quite certainly did this when you used shutter priority mode) and still don't get acceptable shutter speeds at maximum ISO, then your equiplement simply isn't up to the task.

Just wondering… Are just the players blurry or the whole image? If it's the latter, then a tripod may help, as the shutter speed must be too slow then even to shoot handheld. That would help at least with "calm" shots, it won't help you to freeze the motion of the players in action of course.

Actually what you're referring to is a lighting issue - apparently there isn't enough. Given that cameras live on light you'll really need a faster lens to do this.

There are a few out there like this. Http://www.bhphotovideo.com/c/product/247091-GREY/Nikon_2137_Normal_AF_Nikkor_50mm.html

You'll notice right away the fast f/stop at 1.8. The only problem is it's a prime lens so no zoom at all.
When ever you use a zoom lens the f/stop is going to be slower because of the length of the lens. Not as much light can reach the sensor.

I'd also suggest some experimentation at the field. Set up your camera on full manual with this
50mm and shoot. Look at the shot. If there's not enough light, use all the aperture the lens has and slow down the shutter. Again you're going to get blur and I agree, a tripod will help.

If there's not enough light for even the f/1.8 then perhaps a little higher ISO will work. But, I never shoot above 200 because of noise. I've used 800 and gotten some noise. Below that you should be alright.

Night photos are always tricky at best. Experiment, get the 50mm and work at it.