handicapping the horses, not the jockeys... For the most part, with the jockey, I want to see that he's not huge downgrade in rider.
If he's ridden the horse well before, and/or he has a rapport w/ the trainer, it's usually a non-factor.
There are a minority of bad jockeys who are problematic enough, that even if a horse is coming off one or two trips, I won't invest any or much into a wager, for the reason that the jockey's inept riding is partially responsible and wary of yet another bad trip. I have watch-list horses who pop up w/ two consecutive races against the setup!, and then they are 9-1 and down in class where their good race will contend, and the strategy is "4 wide on the pace 1st turn"
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There are a minority of good jockeys who may fit a certain horse especially well. If there's a loose turf speed, Saez may be a nice fit. If there's a horse who needs to rate, and draft, and time his run, Irad is nice to have up. Prat seems to be a natural to capitalize on position and tactics. Johnny V has really done well to capitalize on position and tactics with a talented runner.