Kdr doesn't make a person good.
depends on gametype but if its high k/d the person 9 times out of 10 will be better
if u want a high k/d the easyesy way is to pick a noob gametype like tdm or domination where all the noobs flock too
use a gun with a silencer, try to get around there spawns ect the normal stuff for maximum k/d ratio on kill streaks use 7 9 11 pavelow is a beast