Rowleyfile: What Difference Does A Change of Jockeys Make?

Jockey metrics have been getting an increased airing in the media and on these pages in recent times, and justly so. While a jockey’s contribution to performance is small compared to that of a horse, small differences are often all it takes to win or lose a race: that being so, the ability of a jockey to maximise a horse’s potential has considerable value.

There are many ways of looking at a jockey’s worth, from crude counting measures – such as “winners ridden” in a given timescale which may serve a purpose in determining a championship – to more sophisticated ones. In the latter category are measures which attempt to establish how much relative value a jockey adds or subtracts in given circumstances.

The picture is complicated by the fact that partnerships come and go between jockey and horse, with the result that effects can be masked. A “good” jockey may boost the achievements of a given horse when taking over from a “poor” jockey, but he or she cannot continue that boost indefinitely: this is another example of regression to the mean (an important concept in statistics as well as in horseracing analysis).

One way of looking at the worth of jockeys, therefore, is to isolate instances in which a horse is ridden for the first time in a given code by a specific jockey. Even then, there is a possibility that the new jockey is benefiting from the ground work performed by the old jockey, and the precise performance measure used to establish worth may also be open to dispute.

The following figures are for jockeys riding in Britain and Ireland since the start of 2009 taking over for the first time on a horse in a given code (Flat, hurdles or chases), with that horse having run at least four previous times in that code.

Only jockeys with 50 or more qualifying rides, and who are still active, are shown, and the tables are for the top 10 in each race code as sorted by “ran to form” (the % of horses that ran no more than 5 lb below pre-race Timeform rating or won).

In what may, or may not, be considered an example of confirmation bias, it is pleasing to see many of the “right sorts of names” there.

Ruby Walsh – who is the best jumps jockey of this (and possibly any other) era according to several independent measures – is top of the pops in both hurdles and chases; Tony McCoy – who is outstandingly hard-working, consistent and, of course, talented – is well up there in both those lists.  

On the Flat, the exceptional Ryan Moore is pipped by Olivier Peslier, whose occasional forays to Britain are more targeted, but otherwise comes clear of the pack. The gifted and grafting pair of George Baker and Richard Hughes gets a major look-in as well.

It can also be seen that a handful of amateurs make the Flat list. This is not because they should be mentioned in the same breath as Peslier, Moore et al, but because they have been judged in their own immediate context.

There is far less crossover between amateurs and professionals on the Flat than over jumps, and Serena Brotherton, Simon Walker and Carol Bartley dominate their amateur peers in a manner which only top professionals do to other professionals.

Shout-outs also need to go to the various apprentices/conditionals, and former apprentices/conditionals, in those lists, such as Alistair Rawlinson on the Flat and Maurice Linehan over hurdles.

Sadly, establishing that Ryan Moore and Ruby Walsh are highly successful jockeys when taking over for the first time on horses previously ridden by others is not a passport to riches!

The public rates these individuals very nearly as highly as the statisticians do, with the result that backing their qualifying mounts would have lost about 10% of stakes at Industry Starting Price. Additionally, it can be seen from the MEF values that Ruby Walsh’s first-time presence roughly cuts a horse’s odds in third while Ryan Moore’s roughly halves it.

More profitable strategies would have been to back the following jockeys when they rode a horse for the first time:

Flat: Jordan Nason (16 wins/106 rides) +90.6% Return On Investment; Mirco Demuro (12/87) +82.0%; Sam James (13/78) +77.3%

Hurdles: Nico de Boinville (15/63) +106.3%

Chases: E. J. O’Connell (10/63) +68.3%

What is clear is that jockeyship, like equine performance, cannot be captured entirely in just one number. Context as well as overall ability is important. Some jockeys are more consistent than others, some habitually take up certain positions in races more than others, some perform better on certain tracks than on others.

A jockey’s record on horses he or she has not ridden previously is a persuasive piece of evidence, but it is still just a part of a bigger picture.

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