I have already had my D3S rebuilt once and it is long overdue for an overhaul. The acquisition of the D4 just makes that time so much more palatable. The D3S now has about 850,000 shots on it. I am going to get it addressed and use as my backup.
Actually what I was trying to convey is that the original problem I have actually has nothing to do with the available light, artificial or natural. The behavior the camera exhibits is like it is bracketing a shot and bracketing is not turned on. I can shot a 12-15 shot sequence of a sports sequence and 2 are over exposed 3 are correct and 4 will be underexposed, same light, same conditions, etc.
In addition, it seems exaggerated when I shoot with the camera in portrait mode.
I am guessing it has to do with the shutter timing and exposure, and perhaps fatigue.
The problem you describe is a documented nuisance of sports facility lighting.