Ok, not getting into historical debates:

My recollection of MTW was that you didn't want your polearms near a cavalry charge - I distinctly remember attacking a unit of routing light cavalry with dismounted chiv knights and my knights getting run over- ok, not a direct example of a normal cavalry charge, but I do remember that in MP, I always had my heavy polearms on the wings behind my main infantry line so they could flank already engaged cav/inf units and do them in - i always tried to keep them away from direct first contact.