Hmm. Even if there isn't some amazing coefficient made to rate was performance, what's stopping EE having weekly medals of some sort for different categories related to gameplay, like most money made off market sales, best land grabber or best grab, most successful attacks, most successful defends, even the highest networth. Could even have some that were still given out weekly but were based on whole set averages like defense or attack who percentages on either land based or was based attacks .
Calculating winners on a weekly basis would take very little resources but would give every player somethins to strive for other than winning top networth. These could be done on both a clan basis and individual basis.

Stuff like this will keep new players playing far more than an amazing coefficient for war performance would, as much as it pains me to say that. Would be great for the developers to find a way to rank war clans as they do netters, but why stop there?