Wilder probably did knock Haye down. They have sparred for weeks and Wilder is a KO artist. He probably landed some great flush shots on Haye's jaw every day for 4 weeks. Lots of people get dropped in sparring. So what? What does it prove? Absolutely **** all. It tells me Haye is having some great sparring and will be in shape to finish Fury within 5 rounds.
It's possible that Haye got caught off guard and dropped. The question is how many times Haye dropped Wilder? I could imagine a good 5 or 6 times.