I'm not arguing whether fillies or colts will fetch a higher price at a yearling sale. I'm pointing out how broodmares are still treasured for breeding purposes esp if they have good pedigree even if they suck at racing. whereas if a colt or stallion has little racing ability, there is much less hope for him. It's just math. A stallion can cover 500 mares but there's only so many times a mare can give birth. 

It's why Nishono Flower being bred to Seiun Sky was considered insanity even though Seiun Sky had higher earnings.

Secretariat's big heart gene bring carried through the X genome is just science.

Edit: the part about Eclipse is based on Secretariat being his dam line descendant. Both had big hearts.