By their play style. If they want to be a hero and take care of clearing rooms for you, count me out. I want to play too. Do you revive and support your teammates when needed? Yes, then yay. Do you constantly NOT pay attention to somebody carefully aiming with a rocket launcher and ALWAYS get in front of the shot at the last minute, then you gotta go. Do you get in the way in general outside of minding the space? Yeah I know its tight but you need to pay attention. Can you communicate without 3x the background noise (You're playing your game, watching TV, have the radio on and have family/spouse talking loudly at the same time) GO AWAY. Grim score is nothing but repetition. It doesn't reflect any skill. So I don't care about it, nor look at it much.