Well the origininal suggestion regards turret moving deviation, but any additions or modifications are welcome.
As said above regarding movement deviation, this could be seriously reduced when driving at low speeds given there would be a shift key=infantry speed option.
If turret deviation is possible, it would encourage flanking because the defending tank can't just turn the turret and fire. It'll need some anticipation and planning to kill the assaulting tank.
I mean it's just wrong!
A shell cannot just fly out of the barell in a wrong direction!
Maybe to blur the sights or something like that but putting deviation would be apsurd!
MG's already have deviation. That also makes no sense, but you'll have to understand that deviation is the only solution in BF2 on how to tackle movement/settle penalties. Deviation resembles the time it would take to find a good position to lay down your gun at, judging the distances etc. But that can't be animated thus there's an accuracy penalty.