By Derek Simon
George E. Smith
There’s an old racing axiom that claims “weight can stop a freight train.”
In fact, many old-time gamblers like George “Pittsburg Phil” Smith felt that weight was the preeminent factor in thoroughbred horse racing.
“In handicaps the top weights are at a disadvantage always unless they are very high class horses,” the legendary gambler noted in “Racing Maxims and Methods of Pittsburg Phil.”
Yet, with the advent of speed figures and trip handicapping in the late 1970s, weight became a forgotten factor. In fact, Dr. William L. Quirin provided statistics in his 1979 book “Winning at the Races: Computer Discoveries in Thoroughbred Handicapping,” proving — or so it would seem — that weight was as meaningless as a politician’s campaign promises. According to Quirin’s research, top-weighted horses actually won more than their fair share of races, not less, as Pittsburg Phil and other gamblers of yore asserted.
In an updated version of “Betting for a Living,” originally published in 1990, British author Nick Mordin sided with the contemporary view.
“The idea of downgrading a horse’s chances when it carries more weight seems quite attractive and logical at first,” Mordin wrote. “After all, a horse really ought to run slower if you put more weight on its back. So if one horse lost narrowly to another the last time they met it should reverse the placings if it now carries comparatively less weight.
“This is a fine idea in theory,” Mordin went on, “but it doesn’t work in the real world — as you can see from a survey of 222 races selected at random from the form book over a three-year period.
“In these races there was a rematch, where two horses met again having finished close to each other in their previous race. That is, they finished next to each other in their previous race (e.g. second and third, or fourth and fifth) or within two lengths before they met again. This is what happened when the old adversaries took on each other again:
“When the weight remained the same or the loser carried relatively more weight, the loser lost again 56 times out of 96 — or 58 percent of the time.
“When the loser carried relatively less weight than the horse who beat him, it lost again 73 times out of 126 — again 58 percent of the time.
“On average there was a weight shift in favor of the loser in these races of 2.45 lbs. According to the age-old handicapping formula, that kind of weight shift should have been enough to reverse the placings in the majority of races in the survey.
“But it didn’t happen,” Mordin concluded.
Another study, conducted around the same time as Mordin’s, by Ken Massa of Handicapping Technology & Research, produced similar results — both in terms of the effect of weight on performance, i.e. finishing position, and the effect of weight on speed figures, which Massa termed “inconclusive.”
However, Massa also pointed to subpar ROI (return on investment) figures as possible evidence that weight may, in fact, have some influence on results.
Still, with all the evidence that a few pounds up or down doesn’t matter much, it is clear that many trainers and owners believe it does.
When Blind Luck edged out Havre de Grace in the 2012 Delaware Handicap, Larry Jones, trainer of the runner-up, felt that weight played a major role in his filly’s defeat — and he wasn’t shy about sharing his opinion.
“Tell me two pounds does not make a difference,” he groused after the race. “[Blind Luck] won six Grade 1’s versus our one and we are the high-weight? That makes a lot of sense. I probably should not have run.”
Hence, we are left with an interesting dilemma: Do we pay heed to the handicappers and studies and dismiss weight as a handicapping factor or do we give credence to trainers and racetrack insiders and pay attention to it?
The answer, I believe, is the latter — not because I think the studies are bogus, but because, in speculative ventures, perceptions matter. If, for example, the majority of bettors believe that horses need to be “rested” to perform at their best, the odds will reflect this… and, in fact, they do, as I recently demonstrated with horses coming off big wins.
An earlier study I did further drums home this point, as a sample of 1,010 horses carrying more weight than the race conditions stipulated (“over-weights”) produced a 0.85 impact value (IV) and a 0.73 odds-based impact value (OBIV).
Again, I doubt this was due to the additional weight that these horses were forced to carry, but, rather, it had everything to do with trainer intentions. Trainers with a fit-and-ready steed are looking for any and every conceivable advantage, so why make the task at hand any more difficult by carrying extra weight?
With this in mind, I decided to conduct a very simple study: I looked at horses that added or subtracted a significant amount of weight from one start to the next.
The results were stunning:
In both sprints (races less than a mile) and routes (races of a mile or greater), horses adding 10 pounds or more from one start to the next were at a significant disadvantage. Conversely, horses dropping 10 pounds or more from one start to the next actually showed a profit in excess of 14 percent.
Now, I’ll admit, despite the 
large sample size, I have trouble believing that such a humble protocol will continue to yield positive results. As I’ve noted before (some might say “ad nauseam”), pari-mutuel markets, just like other speculative markets, tend to be efficient — meaning that obvious edges, once revealed, quickly dissipate.
However, it is the greater point here that I think needs to be emphasized: The very fact that trainers and racing insiders believe that weight is a crucial factor makes it a crucial factor.
