A top bitch I was involved with came about like this! A rural product salesman/ dog trainer gave away a non chasing bitch to some dairy farmer customers who became interested in dogs, they went to the nearest possible sire (20 min away) who was not a big name sire and bred a litter!! No thought whatsoever went into a sire. This litter produced a Sydney Cup winner and the rest of the litter all won races at TAB class, Yet after that first litter when the advice started coming I think she only threw one more half decent chaser!!
My point is you have to be lucky!
If your breeding to sell you need a top Sire, but if your breeding to race them yourself you can afford to take a chance on a lesser light!