That's what I would have said prior to reading the Deeds of Don Pero Nino.
Some alternative possibilities:

-Longbow forced the French off their horses, forced them to march through mud into a cramped front where they were cut down in hand-to-hand combat.
-Modern replica armour isn't as good as the best Medieval kit + modern bodkin heads are better than the originals.

Before discussing this further, I'll have to revisit some of the plate vs longbow battles... I see you've added another post, but I'll let this stand for now.