Mark, there is a big difference between the pace of a 6 furlong sprint and a 10 furlong route. The Derby fractions were quick for that distance and for that distance at that track. More importantly, the horses on the lead stayed there all the way around. They ran fast and didn't fade. The same thing happened in all the Derby preps that day. The track simply favored speed horses.
I didn't hear whether they sealed the track earlier that day or not, but - judging by the results and the amount of rain that came down that day - they must have.