I don't even think I ever got a 58 kill game, but my most was probably close to 50 on Black Ops. Whenever I get a decent amount of kills, it's usually accompanied by close to the same amount of deaths. I don't care about KDR, but I still want to do good. I don't even get 30 kill games sometimes, which might be why I'm ranking up slowly, unless 4 days is good for 3rd Prestige Level 71.
Were you guys not that good on your 2nd COD game? (MW3 is second, as you can tell. Started with Black Ops)