The Breeders’ Cup World Championships is the ultimate handicapping puzzle for horseplayers, and it’s especially appealing to those who adhere to the maxim of “bet a little to win a lot.” The 14-race slate brings together great horses from all regions in the U.S. as well as from overseas, which means that year after year, top-class runners with full résumés go off at odds far higher than they would in any other setting.