One swallow does not a slightly declining stretch make, on that we agree. And anything can happen for a day. The "theory" at issue was news to me. If there's 30 years of data on closing fractions in dirt races at Oaklawn, as compared to say GP or Aqu, I'm happy to give it a look.

Not all abnormal results cry out for explanation. But, this seemed like a big outlier. A quick look at the past few weeks suggests it occurs a Oaklawn more than at other tracks, but as you say, it would show up in the long term data if there's something going on.