Unfair Advantage in BG Borderlines on Cheating! Blizz Turns Head! Says "Working as Designed"!

I don't understand how this can happen.

I was in WSG doign the GNERDS achievement, getting a lot of kills.
Also dieing a lot but then again so was everybody in there both Horde
and Alliance.

One time while riding back from the graveyard a mounted Horde starts
bearing down on my hunter so I decide to circle around and make him
chase me around the outer skirt and I am going to lead him to where
the bigger battle is taking place.

Okay now something is not right. We are both mounted and somehow I am
taking damage from him. He is a tauren druid. Still how the hell can a
mounted druid be giving me damage while chasing me. That is total and
utter BS!!

I don't care what anybody says. This is lame!

Who is the Banjo Boy that designed this so that can occur?

Well not that it matters much because I got many kills and got the
GNERDS achievement. I hate BGs and wil llikely only go in to get the
GNERDS acievement on my son's toons and maybe a few of my other toons.
Still I just had to rant because something is just off the wall for
that baloney to happen.