All these are important depending on what game mode you are recruting them for. Bc on my newest character I have a 1.7 kd but a combat rating of 80 bc I mainly play rift right now and I only grab the spark of my teammates are failing me but mainly I just play support and try to clear out the enemy so my team can get the spark and then I push up so they can dunk it. This play style will net you a low combat rating but yet I would consider myself playing an important part on any rift team But on the other hand my old one has a kd of 1.3 and use to have a 140 cr back before rift when I would play control, rumble and tdm and be at the very top of the board mostly. So I guess since most think cr is most important Bungie should add a cr stat to each game mode