[quote=@Flamelord]
<Snipped quote by Sublimation>

Fair enough. Actually, those two had the best chance of winning all things considered, since Lancer could just give everyone unhealing wounds, Kayneth helps him retreat, then they wait until they're walking zombies, and off them. (So it was explained to me)

Sadly, Lancer is an honorable guy, and Kayneth is...himself.
[/quote]

Kayneth entered the war to make himself look better and thought he would stomp everyone utterly. As a magus, he is far above the likes of Tokiomi and would easily destroy him in an actual fight. Unfortunately Kiritsugu cheats and has an overpowered mystic code.
If Kiritsugu wasn't there though Kayneth would have won most definitely. A sixth generation head is quite significant, and on top of that Kayneth is a genius prodigy.