What are your settings? I'm guessing u need to be close to 1/500, ISO 3200 to 4000, and 2.8 ?
I shoot all kinds of sports, so I understand bad lighting and fast action....it's tough, sometimes it's just too dark and there's not much you can do but accept that the image quality won't be great.
The key is to get the right exposure, one trick I use (and I know a lot of low light shooters use, is to "shoot to the right" in manual, which basically means you've overexposed the shot by 1/4 or 1/3. It's much better to have a shot slightly overexposed compared to underexposed when shooting in low light conditions.
Another thing you can do is improve your editing workflow. (Master Lightroom or Aperture) For me, with every image I feel is worth editing, I take it through this workflow:
1. Straighten the image
2. Crop image to make it more interesting
3. Work on white balance and exposure
4. Check the colors
5. Sharpen and then reduce noise if necessary.
examples (I edited these with a free App on my iPad, you could get better results with Lightroom)...original and then the edit, the second one is a great shot by the way...nice reaction and you see the downed fighter's hand indicating he is out...nice job.
So two pieces of advice, shoot to the right and work on your editing...good luck.