Just a quick unscientific review based on Tgraphs archives from the last 4 Derbies.

I identified three 5 point plus top horses that ran their top in the race prior to the Derby:

Indian Express
Castledale
Millineum Wind

All three crashed and burned.

I Identified 7 other horses that ran 5 point tops prior to the penultimate race. These horses maintained their form after the 5 point top and all ran credibly in the Derby retaining good form without an X to the moon. Dont' quote me on this I relied on memory after a quick scan. In other words they had more bottom and only one won. At the same time theres some nice horses on this list and its just as likely circumstances lost them their derbies and not belated effects of a 5 point move.

War Emblem
Megadeath
Empire Maker
Peace Rules
AtswhatI'mstalkinabout
Buddy Gill
Ten Most Wanted

What they all have in common are competent trainers probably using the "latest" in "nutrition". (Perhaps with the exception of Hofmans and Millineum Wind)

Does it mean 7 point mover Bandini or 5 point mover Bellmany can't win? I don't think so, they've both got cream trainers and if the figures are accurate they can regress 2-4 points and possibly win. But the last big move on spotty foundation has to be factored along with the other variables.