The Thoroughbred Link employs female families as strains.
History tells us the Bedouins tracked horse ancestry through the maternal/females lines and not by the paternal.
The family-strain carried characteristics.
Whilst speed is the aim, the two bred elements of sire & mare should be dominant complementary carrying on-going stability of breeding in the cycles of genetic regeneration or rotation.
Many sires have superior racing performance, but many are not ‘true’ breeders(progenitors) and the mares breeding aptitude may be for speed, staying or both.
Much depends on family breeding generational cycles over the generational phrases upgrading (or downgrading) but hopefully balanced according to sires used.
It is to view the interwoven strands of the entire pedigree of the horse and to place characteristics of breeding upon the pedigree.
The phenotype (physique) ‘works’ from pedigree but also the way inheritance wants to or does not work.
Always search the ‘strength’ & bone, in shoulder, length of croup and good length of hip with a good head to match. These hand-in-hand are intelligence, agility and impulsion to gallop.
Is there efficiency and economical ‘physics’ of the animal i.e. the way it walks or holds its ‘presence’ through the eye.
Put it all together as it equates to ‘balance’ and a behaviour which conveys an unique presence.
The very thing which catches the eye and says “I’m a winner”.

Tavistock ‘wows’ his audience (photo by The Thoroughbred Link)