This game is very unique , simply because thereally is no numerical value between players. Anyone could be defeated at any time. The enemy just has to make the right decision during decisive moments. And because strategical and tactical planning is needed to obtain adequate conditions for the highest posibility for victory , same could be said for your enemy because he will try to use his own tactics and strategies to defeat you in turn .
We can then safely assume that , along with terrain , matches would primarily revolve around Strategies, tactics, counters and a bit of luck .But let's just say that General A can beat General B , But he can not defeat General C , however, General B would lose against general A but win against general C because his method of waging war greatly suits as a counter for the tactics of General C. Who then would Will have the highest rank?
I am not completely against your Idea for having a ranked system available. However , I am against measuring a general's ability by a number. Because in this game anyone could win , corcumstances arise that changes thhe balance of power, so it might not be easy to assume that an 8TH ranker is weaker than the 1st ranker because by technicality the 8th ranker still has a chance of beating the 1st. But what about rank's 7-2 ? If 8 could beat 1 then does that mean 8 automatically jumps to 1 ? If so then that means that the ranks would change frequently and it would there be a inaccurate list.