>1 means you're above average. 0-1 means you're below average. Remember, for every kill there is a death except cases where you blow yourself up. Therefore the number of deaths on the whole is greater than the number of kills on the whole. If you kill more than you die, you're generally doing well. But this is only very broadly speaking.
KDR depends greatly on what your role in a team is. Assault and Hunchback players tend to have lower KDRs as part of their job is taking damage for everyone else - meaning they also die more often. Light mechs and snipers/LRM boats have the job of dealing more damage are not really supposed to take any, so they tend to have higher KDR.
Chassis also changes a lot. My own KDR varies from 0.94 in the worst mechs in the game (COM-3A, SDR-5K) to 7+ in the cheesiest mech (RVN-3L). People who cheese in a RVN-3L often, and even drop in 4mans with nothing but RVN-3Ls in the 4-man, can reasonably be expected to exceed 5, often 10 in KDR.
Unless they are really terribad.
Also consider lag factors. If two people shoot at an enemy mech with enough damage to destroy it at the same time, the one with less ping will get the kill every time.
So what is 'good' is hard to determine since it depends on what you're piloting and who you drop with. You could have a KDR of 4 in a RVN-3L with 4man drops and 50 ping, and you could still be a bad player anyway. And if you PuG only in a SDR-5K with a KDR of 3 and ping of 500, you'd be probably considered as godly by any player who knows what that means.
WLR better reflects your ability to contribute to a team in the long term. If you only killsteal your WLR will be terrible even if your KDR is good since you're not actually doing much to help. But WLR is still biased by how good your chassis is, how good your teammates are and even the time of day (some times have more good players than others, more cheeserunners than others etc etc) and isn't very good in isolation either.
ELO would probably be a better stat value to base your estimates of skill around, but unfortunately we can't see our actual ELO scores. And even so, there's a limit to ELO - once your skill level is high enough it may become impossible for the matchmaker to find an actual match for you within the matching timeframe, which means that even if you drop alone, your team may end up overpowered far more often than not because it contains one of you. If you drop with 3 friends that all exceed the ELO's normal limit... the 4 of you can very well have a greater level of skill than the entire 8 mech team on the other side combined.
Edited by Hayashi, 08 April 2013 - 11:48 PM.