Defense in Wintergrasp is enjoying what seems to be around a 90% win rate. While I have no statistics to support the number other than my own experience and observations of other players’ reports, the BG is clearly heavily skewed to favor the team on Defense.
I think the single greatest factor to this imbalance is the 8 vehicle advantage that the Defense enjoys thanks to the 2 free workshops sitting in the base. Once the Defense is able to build vehicles, the advantage is just too great and the advantage snowballs into inevitability.
Get rid of the 2 Workshops inside the base. The base is already heavily fortified with NPCs, Tower Cannons, RPGs, and plenty of ledges for ranged DPS to fire from relative safety. Removing these 2 interior Workshops will make the BG far more competitive.
It would also probably be worthwhile to reduce both the baseline duration of the BG as well as the time reduction of toppling a tower. This would serve to keep the average duration of WG matches from climbing to even longer durations and tanking queue times without too harshly punishing the team on Offense.
No seriously, Blizz. Fix this disaster already. There is no way you can sit there and look at the difference in win percentages between offense and defense and think that this is okay.