Strangely enough, my kill record has gotten worse as the versions progress. I've become a better player, it's just not reflected in my player profile. Mostly I think it's because I stuff around for the first couple of weeks in each new release checking things out, save scumming to play with new assemblies etc. I used to just be concerned about winning, now I like trying out the new content, builds and medals/challenges.
That, and I'm stupid. If my missus asks me a long and involved question, I usually like to pretend that I can think, talk and play computer games at once. I can't. Deaths are inevitable in this situation. It's probably not her fault, although I blame her all the same.
So to answer your question, you know you're a bad player if you play like me.