Funny, I win most of the WZs I'm in.
We Imps on the server have several issues to deal with: not as many Repubs, so our PvP wait times are higher; several bugs that tend to favor Repubs (the sage healing bug, which has been fixed, being a huge one!). As the Imps start to get better PvP gear, the WZs will be better matched. Repubs get queued much faster, and got geared out much sooner, making it much harder for the Imps.