Jimbo,

I make my best effort to discount the horses chances due to the jockey's riding style.

I'm a big believer that when horses get loose in moderate early fractions they are getting optimal conditions for running their best possible figure on that day and potentially slowing things down enough to hurt some of the closers.

There's 3 major problems with predicting something like that.

1. It takes a lot of insights into the horses' running styles, previous fractions, and quality of competition to know if someone might get loose.

2. Horses don't always run back to their recent typical style. Some show more or less speed than usual, get a bad or extra good break etc..

3. Many jocks aren't too sharp when it comes to taking a tactical advantage.

I just weight the probabilities of various horses winning up or down depending on my estimate of the probabilities of various pace scenarios.

Jockey is one of the factors that contributes to that probability.

The same thing would be true of ground loss etc....