I"m with Ruff on this one. The fact that Grand Admiral Thrawn was able to boost his RR from 40 to over 90 in UNDER 24 hours is just mind boggling. And based on the way stats are calculated, there's not even a record anymore of the previous situation. IIRC, if you CD in a game, and your nation ends up being defeated (which is extremely common as people fight over the carcass of the CDed nation), you get a "defeat" instead of a "resign". Then, if you take over a lost cause and lose right away, it's as if you never CDed!!
Part of the solution IMO would be to keep permanent records of CDs. If you CD, no matter if you get defeated, or whatever happens in that game, it stays on YOUR record as a CD. That way, even if you repair your RR by taking over other games, people can still look at your number of CDs to see how many times you've screwed a game over. You better believe that people with 10 CDs and a 90+ RR would be looked at differently than someone with 1 CD and a 90+ RR or 0 CDs and a 90+ RR.