With regards to Frankel, here's another possible explanation for his poor record in the BC. I'm not saying whether I believe it or not, just throwing it out there.

There are about a gazillon graded races throughout the year. Maybe, he is just better than most at spotting his horses. Obviously, money is not an issue when thinking about where to ship. If he is better than everyone else at picking his sports, then that would explain his amazing record througouth the year. But the BC is a different animal. There's no ducking anyone there. Everyone points for it (except Perfect Drift, haha), and the races are much higher in quality with regards to the depths of the fields.

Just another thing to think about,

CC