Beastmen patrols are really weak compared to other patrols because the 1 banner bearer is all that makes it even remotely threatening. And even then it usually dies before planting the standard.
A simple way of making the patrols more threatening without reworking enemies would be to simply add a second standard bearer to the patrol, maybe even a third for cataclysm or higher. You could put the second standard bearer at the back of the patrol since the first one is at the front of it.
A second or third standard bearer will make it harder to effectively kill the patrol early but can still be done consistently with coördination and a good aim.