Nobody has noticed that some of the spearmen actually use the overhand style. Check those first guys the with big beards and crossed shields. Their spearpoints are pointing into the ground. Needed for overhand style (dev talk, long ago).
Meanwhile there is another unit where the point is pointing skywards but they still fight overhand (so the butt of the spear is used in combat). I remember that in the TC show for some of the units. Especially the late Roman auxiliaries.