I've spent a ton of time around horses and have a few thoughts on the subject.

#1 young horses rarely run big negative numbers. They aren't supposed to. When they do, it is often because they're are other factors that led to the performance. A track they relish, inferior competition, favorable pace, etc. Very often in their next race they do not encounter such favorable circumstances and therefore don't repeat the number. The fact is they wouldn't have repeated the number again anyway even if they had had enough rest. The pace, competition, track condition, form cycles and trip will rarely align the same way twice.

#2 Even if a horse does encounter favorable racing circumstances again, big numbers are often gut wrenching efforts that will knock horses out if they don't get time to recoup. Every race either puts something into a horse or takes something out. That is why they have form cycles. If you bring them back in too little rest they are likely to tail off or get hurt, as would any athlete, period. How many people do you think could win a marathon every two weeks for a couple of months in a row verses different fields in different cities. How often do pitchers pitch on two days rest, etc?

#3 Nowdays the Triple Crown races are one of the few times where a trainer will feel compelled to race a horse 3 times in 5 weeks at different tracks at different distances. When these young 3 year olds run big in any of the preps or the actual races, the trainers feel compelled to run them back. So we actually get to see the effects of too much all out racing in too short a time period. We don't get to see this as often in older horses, but I would suspect the patterns would be same if we did. Big races take a lot out of the tank, period.

So in sum, these big races will knock a horse out if they are not given ample rest. In my opinion it is an equine fact. If that tired horses does not get hurt during a gallop, or walking, etc., they still will often not repeat the number either because they are tired or because the race just doesn't shape up as well for them.

A big negative number is like ptiching a shutout in baseball. They just don't happen that often.

Now what odds would you need to get to bet that a pitcher will throw back to back shutouts, much less do it on three days rest. You've got to look at horse racing the same way or you are just giving your money away. I bet Big Brown in the Derby, passed on the Preakness, and played against him in the Belmont. If Da Tara doesn't win that race I am still counting my money...