Alright, it seems like we're using the same word, "Score", in two ways here...
Firstly, "Score" as it appears on the in-game tab menu. And then "score" in reference the Harald's forumla. Not the same, in regards to Performance rating, are they? I mean, one uses all damage you deal to come up with its value, and the other just looks at Kills and Deaths, no?
Check out my results from last night's fight. Seriously, no E-PEEN sizing intended - I'm only trying to point out how strange it is to me that "score" (as it appears on the tab menu) is seemingly ignored by Performance Rating. And again, for the record, I only care because this issue can (apparently) keep me from getting into strat battles, and thus having fun.
As you can see, there are people on that list whose KDr were way, way, way better than mine, and yet I "out-scored" them, sometimes by hundreds of points. Look at Anders, Lorden, Kesh, Syls. Are they better players than I am? Certainly. Should their Performance Rating reflect that? Yes. But what's the point of even having an in-game "score" rating if it doesn't change your listed efficacy?