Stephen Hunt runs the numbers... on his own numbers
Stephen Hunt • March 24th, 2025 1:24 PM • 5 min read
Over the next few weeks, I’ll be explaining what ratings are in principle, why they are important and what use they have.
The first piece I want to present is on the WFA Performance Ratings that I quote in my pre and post-race articles here on Trackside.co.nz
What are WFA Performance Ratings?
WFA Performance Ratings are a numerical measure of a horse's performance, measured by the quality of the race it contested, its beaten margin, and the weight it carried relative to our weight-for-age scale. The higher the number, the better the performance.
Example: Winners on Champions Days – 8th March 2025
Alabama Lass achieved the highest rating of the meeting, a 103, in winning the Group 3 Kings Plate over 1200m. El Vencedor ran a 99.5 WFA Performance Rating to win the Group 1 Bonecrusher Stakes over 2000m. These were the two highest-quality races of the meeting.
Scales and points per length
WFA Performance Ratings are expressed in points on a custom scale. Unlike some other ratings, they do not reflect or directly relate to kilograms or pounds.
At the top end of the scale, the best horses in the country run WFA Performance Ratings of 96 plus, with elite world-class performances rating 108 plus. The champion mare Imperatriz had career peak ratings of 108 and 107.5, with numerous performances in the 104 to 106 rating range. At the other end of the quality scale are country-class maiden winners, who will typically rate in the 72 to 79 range.
The number of points per length varies based on certain race factors. One key reason for this is that a one-length gap between horses at 1000m is not the same difference in performance as a one-length gap over 2000m. That said, working on an average of 2 points per length is a good practical guide to help you understand the difference between horses.
What are WFA Performance Ratings based on?
WFA Performance Ratings take a multidimensional view of assessing performance quality, using a sophisticated array of input factors, algorithms, and personal review. The sections below describe this in more detail.
Race Strength
The starting point in creating WFA Performance Ratings is assessing the strength of each race. Most ratings have a simplistic or limited view of this important foundation. Treating each race as a unique event and using a range of key factors to determine its merit is essential.
The Race Strength figures are not automatically generated by a computer. They are calculated as part of a race review process.
Consider this: a fast time alone doesn't always guarantee a strong race, and a slower time doesn't automatically imply an inferior one. A significant margin between runners at the finish might hint at a better-than-average race, but this isn't a steadfast rule. Even a race with weak lead-up form and ratings can surprise with its strength. Each race is a puzzle, evaluated based on the interdependent relationship between factors, resulting in a unique assessment for that event.
Individual Horse Adjustments
Once the race's strength is determined, the Weight-For-Age (WFA) Performance Rating for each horse can be calculated by adjusting for its beaten margin and the weight carried.
Beaten Margin Adjustment: Traditional methods for adjusting ratings based on beaten margins are outdated and ineffective. WFA Performance Ratings utilise a variable scale that accounts for specific race conditions.
Weight Carried Adjustment: Conventional theories often exaggerate the effect of weight on performance, but it cannot be disregarded. Research shows that weight significantly impacts performance and varies depending on race conditions, such as distance. I compare the weight carried by each horse to my own WFA scale and adjust its rating using an algorithm that more accurately reflects the weight's impact. This approach is distinct from traditional rating systems, which measure weight against an actual or theoretical minimum.
Summary
Remember that ratings are one tool for good racing analysis, they are not the only tool. Racing is about more than numbers. The art form of understanding horses and races is just as important. If you have followed racing for any length of time, you’d have undoubtedly built-up knowledge and skills. Keeping those in play as part of your arsenal is essential. Ratings provide some objective data to help you create clarity, confidence and an overall picture, but also allows you to blend the art form of your knowledge, intuition and judgement with some science from the data.
In the coming weeks, I’ll do a follow up piece on Speed Ratings. I’ll talk about the concept of understanding how fast a race was in each section, key factors like par times, expected rating, comparing raw figures against expected to get an idea of how fast or slow conditions were on the day, adjusting for that and then developing final ratings, which also show the early and last 600m speed of a race.
Picture at the Top of the Page: Damask Rose when winning the NZB Kiwi. Photo: Race Images NZ
