It looks like the individual jockey's stats are generated randomly for each save game file. So my Game1 Dettori doesn't have the same stats as my Game2's Dettori. And I have to admit I was confused with who was rated honest and who not the first time I looked!
So comparing the performance of whatever jockey I used to who you used may not have meaning. But, as to what the stats do, and how they matter, I wonder that too!