I think a lot of the miscommunication and misunderstanding in these pedigree discussions lately stem from the fact that sport horse pedigrees and thoroughbred race horse pedigrees are evaluated somewhat differently.
The basic premise is always the same: good sires and good dams beget good horses. But thoroughbred racing has the benefit of centuries of data about breeding for a single purpose. The data just continues to become more detailed and more accessible.
The pattern has been well established for eons that the production and race records of the dam line or female family are some of the most important factors in predicting success. Specifically, you’re looking for a consistent record of mares along the bottom line outproducing themselves or producing stakes winners. Horses bred from successful producers are more likely to be successful. When thoroughbreds are sold, 3/4 of the entire catalog page is dedicated to the female family. Sires get a blurb about their race record and their offspring. Everyone else just gets their name printed on the pedigree chart; not because they are unimportant, but because history has shown that they are not as beneficial individually when predicting the success of the foal. (also, because it is assumed that their accomplishments are already known) Breeders consider the entire pedigree, but it is the combination of the sire and the production record of the female family that are the best indicators about how the horse might perform. Horses that look like they have a high chance of performing at top levels will be more highly regarded.
Sport horse breeders just don’t have the same volumes of data available about the dam line, regardless of the breed. It’s not because sport horse breeders feel the dam line is unimportant, but because the different disciplines are so diverse. The data is just harder to compile in the same manner for so many reasons that I’m not even going to attempt to name them all. It’s chiefly the stallions that end up leaving behind traceable legacies, so the pedigree on paper is evaluated primarily based on the stallions. You have to infer a lot more information about mares based on who they are sired by.
When many sport horse breeders look at racing pedigrees, I’ve noticed their eyes immediately jump to the sire, grandsire, and broodmare sire. After that, they consider the sires further back. Sometimes they investigate the race records of the dams, but they rarely consider the dams’ production records for what they are worth.
To form a more accurate assessment, you need to include evaluation the production record of the female family, specifically the first three generations. No matter how many well-known sires are seen on paper, the female family is going to make or break the overall value of the horse.
And I hope my (ridiculously long) post does not offend any of the breeding gurus we have here: both for sport and racing. We just seem to be having a lot of circular discussions that go nowhere.