Make no mistake about it jockeys want to be on the best horse in the race, or at least what they feel is their best chance of winning. The better jockeys often get to choose between mounts in races. So it's a good idea to pay attention when a jockey has a few options of which horse to ride. 

This can be a little misleading at times because certain jockeys have commitments to various owners and trainers. This means that they will likely ride for them first, unless they have a prior commitment or a "real nice" horse.

In general though when you see that a better jockey has ridden several horses in a race in their last start and then opts for one of those runners today. You can bet that he is tipping his hand on which one he thinks is the better runner. 

Jockeys, trainers and jockey agents study the form. So they have a good idea of who is the best in the race, but jockeys have that added edge of feel that we can't get from reading the form. They may be working the horse in the mornings and are getting the feeling that he may be coming right now. These are the horses that can pay a price and often times the only tip-off may be a rider switch. 

So when I see a capable jockey choose his mount in a race, I usually have to rely on his judgment, even if the form is telling me otherwise.  Especially at the summer meets like Saratoga and Del Mar where there are lots of top jockeys, who ultimately win most of the races. You have to pay special attention to who they end up on today. Especially if they have made a choice between runners.