The drop rate has definitely been buffed. It was confirmed that they upped the drop rate of the Brewfest mounts because we only got 1 shot per toon per day, so, no only is a reasonable to assume the same of Horseman, a SIGNIFICANTLY increased number of people have either received or seen the mount in comparison to last year. How much it has been increased, we don't know, but I think it's safe to say that it's higher than it used to be.