Sire success: the case for holistic analysis

5 min read
While there are numerous indicators of sire performance John Boyce makes the case for a broader analysis of variables to determine the context of stallion success.

There’s always plenty of debate about which metrics to use when assessing sire performance. In truth, there are many useful and relevant ways to do this. It all boils down to what you are trying to uncover.

Do you want a stallion that gets really good 2-year-olds, or one that also gives you top-class weight-for-age horses later on?

Predicting the rhythms of a sire’s career is an altogether different matter. Breeders nowadays – particularly those who breed to sell – are more likely than ever to evaluate a sire on a year-by-year basis. It’s not that they think less of a sire from one year to the next, although there will be some stallions that breeders either upgrade or downgrade due to results on the track, it’s more a case of them assessing the financial risk to their business of using a young sire in his early years.

"Breeders nowadays – particularly those who breed to sell – are more likely than ever to evaluate a sire on a year-by-year basis." - John Boyce

To survive as a commercial breeder, you are going to be risk aware. Because so many good racehorses are sourced through the sales these days, the commercial imperative has dictated how many a stallion’s career plays out in the early years and even for longer in some cases.

The commercial cycle

We all know that breeders flock to the best new sires in year one. Year two introduces the risk of a sire’s first runners not performing and devaluing your second-crop sales yearling. The same applies to years three and four. Should his first 2-year-olds impress, there could be an upturn in a stallion’s fortunes in year four, or even sooner if his yearlings have sold well.

The first yearlings by Headwater are selling at this year's sales

The upshot is that we get a four-year cycle forming, which makes it impossible to predict the rise and fall and rise again of a sire’s career without this background knowledge of how breeders have supported a stallion. When a sire does eventually get past his early years, the cycle diminishes and it becomes easier to predict future success from present success.

"We get a four-year cycle forming, which makes it impossible to predict the rise and fall and rise again of a sire’s career." - John Boyce

That said, there is still a good deal of interpretation to be done even with the very best proven sires. Most of us have a very good gut feeling of what constitutes a good stallion. But explaining it with data is not straight forward, leading to suspicion when the wrong metrics are used.

Comparing the best in the world

For instance, the two best sires in Europe at the moment are Dubawi and Galileo, who have sired 15.9% and 16.8% Stakes winner to runners. Are they better sires than Australia’s Snitzel, who sires 10.3% Stakes winners to runners?


Clearly, the opportunity to become a stakes winner is quite different in Australia, compared to Britain and Ireland. In the last completed season in Australia, only 1.55% of all runners became stakes winners, compared to 2.35% in Britain and Ireland.

Therefore, we could claim that Snitzel sires stakes winners at 6.64 times the national average whereas Dubawi manages 6.77 and Galileo 7.15 of the Britain and Ireland average.

And what about Deep Impact? His 10.2% stakes winners to runners in Japan represents 11.59 times the average for all runners in Japan. And just to complete the set, Tapit, in North America, sires stakes winners at 5.36 the average for that region. Straight away, we get a completely different perspective on things.

Deep Impact

Active sires in GB, IRE, USA and AUS with 10%+ black type winners to runners

Deep ImpactJPN 1,223 124 10.1 11.52
Redoute's ChoiceAUS 1,238 150 12.1 7.82
GalileoIRE 1,555 261 16.8 7.14
War FrontUSA 514 77 15.0 7.13
FrankelGB 207 33 15.9 6.78
DubawiGB 875 139 15.9 6.76
SnitzelAUS 821 85 10.4 6.68
Uncle MoUSA 352 44 12.5 5.95
Distorted HumorUSA 1,174 144 12.3 5.84
SpeightstownUSA 815 96 11.8 5.61
TapitUSA 992 111 11.2 5.33
Medaglia d'OroUSA 916 100 10.9 5.20
Sea the StarsIRE 404 49 12.1 5.16
GhostzapperUSA 616 66 10.7 5.10
Lope de VegaIRE 364 42 11.5 4.91
PivotalGB 1,271 143 11.3 4.79
Giant's CausewayUSA 1,559 156 10.0 4.76
ShamardalIRE 915 99 10.8 4.60
Oasis DreamGB 1,087 114 10.5 4.46
TeofiloIRE 676 70 10.4 4.41

The maternal influence

Our perspective can also be influenced by the quality of the broodmares in each region. We know that all four regions have some of the world’s best mares, but they are clearly not evenly distributed.

Australia’s 20,000-plus foal crop has comparatively fewer top-class mares than does Europe. With Coolmore, Godolphin, Juddmonte, the Aga Khan, Shadwell, Cheveley Park, to name but a few, Europe has the lion’s share of top-class mares, followed by North America.

One of Australia's top-class mares, Vegas Showgirl

However, this in itself is not guaranteed to give European sires an advantage over their Australian counterparts. When Australian breeders have identified their small group of exceptional sires, it’s arguable that they get outstanding books of mares, simply because they are fewer in number.

From my perspective, sires are best evaluated from within a region. Redoute’s Choice suits Australia far more than Europe. It would be silly to combine his stats for both regions when evaluating his contribution to the breed. The same goes for Galileo, who is far better off in Europe than he was in Australia, or could have been on North America’s dirt circuit.

Given racing’s regional specialisation, it is inevitable that we also have sires that specialise. So, be wary of the metric that tries to encompass all aspects of a sire’s abilities into one number!

Redoute's Choice