Quote Originally Posted by Gookieheimowitz View Post
Fairly cut and dry Crowe :

When a jockey works for different trainers and is not on contract he or she might get listed on two horses or even three horses during entry submission . When such jockey is listed on multiple horses they have to chose which horse they want to ride. This choice is 99% of the time made by the jockeys agent . Based on many factors but for example jockey is named on 2 horses . Trainer A has a nice maiden set to race in a few weeks . Trainer B has a string of horses and jockey usually rides for him but is not contracted to do so. Agent makes deal with Trainer A if jockey rides for you in this race you guarantee the mount on nice maiden . Trainer B wonders why jockey chose Trainer A but is fine with it and finds another jockey.

There are many other factors but this is a good example
When we are talking about a jockey choosing one horse over another in the 5th race at Belmont on Thursday you would be correct, however there is more significance to a jockey choosing to ride one horse over another in a race like the Derby.