Pedigree Theories and Selection Techniques
This is not a valid breeding theory at all but a propagation technique geared to generate sales catalog pages. It's a mistaken premise embraced by some commercial breeders hinging on the concept that any commerical sire or popular sire prospect is a valid mate for any mare whose offspring is intended for sale. In many cases, the justification for the mating is based simply on the value or availability of the stallion season. ("That's a $50,000 season!" or "I have a share in him and she needed to be bred.") This mating theory is often a mistaken interpretation of the breeding adage "Breed the best to the best and hope for the best," since here, "the best" is thought to be synonymous with "the most expensive".
This mating technique is the one most often employed by breeders with no time or interest in pedigree analysis. It's also responsible for setting back the American breeding industry several decades in the late 1900s and continues into early part of the 21st Century, since it promots breeding for sales ring appeal instead of racing ability.
A variation of this "theory" was employed by many commercial breeders during the 1980's when "summer sale quality" matings were geared almost entirely to appeal to certain European, especially certain Arab, buyers. A whole generation of top-of-the-line fillies and mares were mated with the intent of producing a foal (usually sired by a Northern Dancer-line stallion) that would theoretically run well under European conditions. The results muddled the Thoroughbred gene pool to a remarkable degree.
A potentially disastrous variation on this concept which has become widespread in practice is the use of surgery to correct limb abnormalities in an effort to present the most conformationally perfect sales weanling or yearling. In response to the buyers' demands for flawlessness, a large percent of young horses undergo these surgeries, even though history and veterinary research has shown that yes, even horses with imperfect conformation can run well and earn good money. Unfortunately, records of these surgical corrections can disappear after the sale of the horse, and unless they become public record, horses frequently go to the breeding shed as cosmetically altered without the knowledge of the new owners or interested patrons. Breeders inspect stallions who may or may not be genetically what they appear to be after surgery. This can be a costly error, especially if a crooked mare is bred to a stallion who appears correct, but was made that way through surgical correction. It's my humble opinion that record of any surgical correction such as those performed on the legs or throat, should be attached with a horses registration papers and then made a matter of record to potential breeders.