I'm sure it did.  I've been thrown off a horse before and,  even as a fit person with good balance and aerial recovery, that shit was no fun.  That was 300+ pounds of no dexterity or recovery just dumped to the ground and into that fence.  Even if the horse didn't throw him off, he wouldn't have been able to stay on long anyway.   It takes work to sit atop a horse while it's going.