Createure, I think the low orc casualty numbers are due partly to there being fewer orcs on the server and also to the major orc alliances (BSH, BSHx and SCH) being involved in a war that prevented them from participating in the tourney until the final days.
The fact that more "attack" troops died in defense than attack and that more "defense" troops died in attack than defense demonstrates why vets keep harping on the old saw "don't defend with cavalry." And by the same token why it's a bad idea to attack with spears. The attacking with spears part was likely largely unintentional, as spear units that were intended to reinforce a defensive position found that it was taken over by someone else in the interim. I know that was my experience in nCrow and HUGcr.
Given the number of casualties inflicted by attacking cavalry vs. defending cavalry, to take one example, it's not terribly surprising that many more cav were killed while defending -- unless the surprise comes from the fact that so many use cav to defend still.
Of course "desperate times call for desperate measures" and in some cases cav is the only thing you can get to the square in time. In that situation, seems like the prudent solution would be to leave only a minimal cav force making time on the square until reinforcements arrive; sweep with cav and reinforce with bows and spears. This tactic was not universally adopted, however, and if all you have is cav and your cav can't get back home in time to send them out again, you might leave them on the square, as I certainly did toward the end of the tourney.
Edited to add: Bad idea to attack with spears unless you're an orc with thousands of troops, and I'm not qualified to comment on that tactic, since I haven't seen it used often enough to gauge its effectiveness. I've heard it can work though.
Edited by Rill - 26 Mar 2012 at 01:48