From the opposing faction I see the hatred coming from two groups:
1. The noob, who hates anyone who beats them easily chooses the boxer for their focus.
2. The player with more /played than the boxer and claims we need to "get a life". This guy wants things back to normal where his highly geared player can rampage through a disorganized undergeared group instead of running into a boxer.

I've said before that using teamwork in the battlegrounds is akin to cheating. This really impacts the boxer.

The hatred from the same faction is bizarre though. Some people really think you are botting, I suppose this is legitimate. Most of those are quickly converted when I actually talk to them. On Crushride/Cyclone, this is fairly rare. I get lots of cheers in BG's and the worst I get from the tank/healer is usually, "you better not suck".