Lately I've been taking a hard look at final fractions for Kentucky Derby contenders. The Derby is the kind of race where basically every angle has been explored. Some angles mean something and some don't. Closing fractions are undoubtedly important because they give clues as to how a horse is handling the distance and if they might be fit enough to stretch out further. Closing fractions have been a bit of an unexplored area for me since there are a ton of problems with calculating them.
I have long surmised that closing fractions, particularly the last 1/8, 1/4 and 3/8th's, could be an important Derby factor but it is quite difficult to get reliable data or back data of any kind. Calculating the final fractions can be extremely tricky for any horse who did not lead wire to wire. The whole debate over how a beaten length translates into time on the clock has never really been settled. People use a rule of thumb (1 length=0.20 seconds) but that is not always accurate, and in fact I discovered that for the average pace of a 9f race it is never accurate.
What a length translates into over a certain distance all depends on the speed the individuals are covering the distance in. For instance if I were to race someone on foot over 100 yards and beat them by 5 feet while sprinting the time differential between us would be narrow. But if we had a race at walking speed over the same distance and I again won by 5 feet the difference on the clock would be substantially larger. Since we don't have Trakus data for each horse which would calculate the specific times for each one at every interval we have to use different methods of identifying what a beaten length equals.
I decided to calculate the time:beaten lengths ratio for every individual race to ensure as much accuracy as possible. I found that at 9f a length is usually equal to 0.14-0.16 seconds. I then went back and calculated the closing splits for every 9f Derby prep race that was run from 1996 to the present.
Many people have calculated the closing splits achieved by Derby winners over the last 10-15 years but the data is difficult to evaluate unless you're able to see what the winners opposition looked like in terms of their closing splits.
A general rule of thumb has been that a potential Derby winner needs to run their last 1/8th in :13.0 or less, their last 1/4 in :25.4 or less and their last 3/8th's in :38.0 or less. Those have been decent benchmarks for the last decade but as most of you know I am generally opposed to arbitrary lines.
In virtually every area I prefer averaging because I feel it is more relevant to the specific race. Much like my theory regarding the Beyer "fast enough" line, it is only important to be fast enough to beat THIS field not all the Derby fields assembled over the last decade.
So I decided to calculate and average all the closing splits in 9f races of every Derby contender from 1996 to the present to see if the winners generally conformed with the field average and how those that didn't fared. If a horse did not have a race at 9f then no closing splits were calculated and that horse was excluded from the stat. In a case such as Charismatic, who ran his last prep at 8.5f, you take the splits from the last time they ran at 9f. In Charismatic's case that was the Santa Anita Derby. I also excluded all horses who were beaten by more than 20 lengths in their 9f start. The fractions of a horse who is virtually eased are not relevant when attempting to determine how fast a horse must be able to close to beat the rest of the group.
I found that the averages often fell in line with the general rules of thumb but there was always a variance. For the last 1/8th the necessary closing split varied from :12.7-:13.5. Some races were simply slower, or rather they contained slower horses.
There were 214 starters in the Kentucky Derby from 1996 to the present. 20 of those starters did not have a race at 9f that could be calculated. Of the 194 remaining starters I found that 109 of them failed to run faster than the average closing split for their field in either the last 1/8th, 1/4 or 3/8th's. Their cumulative Derby record is an astonishing 109-1-7-5. That means the other 85 horses who did run closing splits faster than the average for their field went 85-11-5-7 in the Derby.
Needless to say it appears to be an extremely important factor and it could have a real impact this year. The field is not set so it's impossible to tell what the averages will be but as now they look like this.
1/8 = :12.8
1/4 = :25.1
3/8 = :37.5
Based on those averages Big Brown, Adriano, Anak Nakal, Cool Coal Man, Court Vision, Denis Of Cork, Gayego, Smooth Air, Tale Of Ekati and Z Fortune will find it difficult to close out this year's Derby. They would still have to be thought of as having an excellent chance of hitting the frame, since there was hardly a year when at least one of the top three did not qualify with this angle. But in terms of a winning chance all of these horses could be up against it.