Frank -

The downhill hypothesis is not original with dsipes. Below is an example from Ed McNamara writing on ESPN in 2003:

SIR CHEROKEE
Trainer: Michael Tomlinson
Rider: Terry Thompson

Went from last to first to pull a 55-1 shocker in the Arkansas Derby. Where did that come from? Closed strongly into the slightly downhill stretch at Oaklawn, getting the final eighth in 11 4/5 seconds. He'd never done anything remotely as good, so my gut feeling is it was a fluke. His odds will be huge, so if you think relative unknowns Tomlinson and Thompson can win this country's biggest race, empty your pockets and dream on. I don't see that happening.

http://www.espn.com/horse/triplecrown03/s/2003/0427/1545558.html