Multiplayer has always been the go to for those 2 games. More so for cod. I'd bet 80% don't even play the cod campaign and go straight to pvp. Halos pvp is amazing, always has been. Personal preference aside, you'd have to consider the fact that cod always has great sales numbers and a high player base. So by that standard (wether one likes or dislikes their pvp) it's good. And that's why they haven't and won't tank.