You guys made me do it... I went through the play-by-play and recorded each rush (grey dots), along with whether or not it occurred before or after Norton's injury. I calculated Yards Per Carry (blue dots), as well as the 95% confidence interval for the average (blue hashes).
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Up to the point Norton was injured, Norton and Brock were giving roughly the same expected yards per rush. But because of the limited number of carries, it's ridiculous to think that Norton was easily the better rusher on the day. Prior to the injury, Brock had the longest run of the day. After the injury, Brock continued to perform at a good clip. You can argue all you want about qualitative stuff - running style, how much they sweat, etc - but qualitatively you can't say that Norton was better than Brock with any certainty. They both played well, but only Brock had enough carries to even start talking about who is better from a production standpoint. Anything said about Norton is still conjecture.