Flanking manuvers will give the advantage to the Flanker and not the Flankee. It gives a bigger target and also gives the element of surprise for someone to come from the side. Also I don't know how the smart the AI is to be able to make a good guess at how vehicles will react to flanking attacks. Just remember that if engaged to the front then a flanking manuver will be very effective. If not engaged to the front, then the vehicles will prolly react to the flanking manuver better.