Robert Bouknight , Feb 17, 2013; 07:00 p.m.
This year, I tried a 28-70/2.8 AF-S, and 70-200/2.8 versions I & II along with the 85/1.8G for shooting BBall. When I had 3-4 more stops of light with good color rendition at the center court at one tournament that was lit to college broadcast levels, the 70-200VRII I had with me ruled and the images looked fantastic. But when I am at the home court and forced to 1/640-f/2.5 @ ISO6400ish (I use manual mode, let the ISO float for exposure), the shots just lock cleaner and more detailed with the 85 prime at 2.5 vs the others at 2.8. I am pretty sure that a good part of the image quality improvement is a result of about 1/2 stop less needed ISO (the T value of the lens factors in, also).
I could go on, but back to the OP's question, I think that the 85G is a good choice in truly dismal light. AF seems fast enough to track BBall action. No doubt that a D4 with a 2.8 zoom or a 200/f2 would be better tools. I wound up leaving the 2.8 zooms at home for most games, but would use them if I had another 1.5 stops of light. I have a 105/f2DC that I have tried also, but had less AF success with it. It would probably be OK if I were a little further from the action, though.
BTW, I don't have any statistics to support, but it seemed like my in focus keeper rate improved when I changed from the 85/1.8D to the G version last year, using a D3s.