It's as John says, there is more randomness to jump horses. I think a full potential bar is the most important bar although my best horses usually have a decent extra speed bar.
I have posted 2 pics below. The mare is my best 2m chaser and wins 2 out of 3 races whilst the stallion wins about 1 out of 5 races when running in the CK.
If bars were everything, then the stallion should win everytime. I have about 50 horses with bars like the stallions who can't finish within 5 lengths of the mare.
Jumping ability is not so important. Some of the top trainers have horses with no jumping ability winning G1 races in the online league.