Can someone please ex[palin the LBs to me.

The Current leader of the Jumping, Irish Sport Horse mare has bred SubSW, SubPW, SubSW and SubPW. I have a mare that has bred WWE, EWW,EEE.EEE and EWE. How does this work?

The Jumping leaderboard is specifically for the jumping discipline

The LBs for Jumping, Cross Country and Dressage work just the same as the Eventing LBs only except that only the named discipline counts for the placing. So in the jumping LB there are horses very strong in that discipline and that discipline alone (dressage and cross country don't count for that specific rating). On the eventing LB a horse needs to be strong in all three disciplines. So the mare you've named as an example has produced a lot of Ws in jumping and will herself be very strong in that discipline. While your mares might be producing the stronger average foals for eventing but aren't as strong in that specific discipline.