AFK farming is possible, but if you think about it, those that are AFK will not get as many points as the leaders. Because they won't be able to be registered in the ranks. You have to hit someone in ordered to get registered so if they're Afk no one really will get a good amount of points.
The way I intend on making the wins fair is, the parties will rotate on who gets first place.
So lead will get the first one, then the person second down the list will have the second first place on the second win, third on the third win, 4th person on the 4th win. Then you restart. I expect the other party to be honest about it aswell so that way everyone has a chance to get the first place amount of points awarded to them.
But yeah afk farmers won't really be good for those afking. I'm not sure if it's worse on the people who aren't afk but I think it might be..