From what I've read (not a whole lot on the germans so don't take my word as law), it would seem that the "Boar's Head" wasn't intended as a wedge shape, it started off as a square but as it approached enemy lines for the charge the senior warriors along with the chief would rush forward first (the chief being front and centre with his retinue either side) with the less experienced men on the flanks having a tendency to hang back, thus producing the "wedge" shape that the ancient historians attest to. I'm sure one of the team can fill us in