Jockeys are important.

MAXIM

As factors in handicapping, jockeys are relatively unimportant. Most of them can give a contender a good ride. The exceptions are stakes races and grass races where the finishes are routinely close and driving. Low-percentage jockeys have a more difficult time defeating their more talented colleagues.

The important fact to remember about jockeys is that they can be important in combination with other changes, such as a drop in class, change of surface or distance, or change in equipment or medication.

Trainers do prefer certain jockeys when the horses are especially well placed, so trainer-jockey combinations in combination with any other interesting change can be a sign the barn expects to win or run close. This is local knowledge handicappers must accumulate through experience or in consultation with statistical products that supply the information.