Actually, when it comes to the Derby (or any race), there is no one most important thing. But a couple of things to bear in mind in these discussions:

1-- As we have pointed out in the last couple of Derby seminars, over the last 150 or so horses that have run in the Derby, only about 7% have run new tops. Last year the top two did, but that race also collapsed (for some combination of reasons disussed hear at length at the time), and none of the fast horses ran their races.

2-- The last two years, there were around four horses each time that went into the race a lot faster than the others. This year it looks (so far) like an awful lot of horses will have tops in a very tight range.

3-- Last year-- when the race collapsed-- the fast horses were coming in off huge jumps, which as discussed at the time hasn't worked so well in the Derby. This year... ?

Sheets and seminars for past Derbies can be found on this site.