Personally the grimoire score, like light and to extent K/D, give no indication of the skill level as it can vary day to day, take myself for example I have 4000 some odd grimoire and a K/D overall of about 0.8, nothing amazing, is this an indicator of my ability....no because I have good days where I play like a ninja but equally I have bad days when you could be forgiven for thinking I'm playing sitting upside with my pad back to front, it's all about the moment and not a score for me others I'm sure would disagree.