I would say that first you look at their SPM and see where they sit on the lobby leaderboard. I'd say anywhere within the top 200,000 players for that particular gametype means they're pretty good (of course this also depends on the popularity of the gametype). Secondly, look at their K/D ratio. If they're within that 200,000 top players and they have a positive K/D ratio, I'd say they're quite good. I'm pretty good at Kill Confirmed, I'm ranked 56,631 with a SPM of 493 and K/D of 1.75. That being said, Kill Confirmed isn't as popular as TDM, so I'd be ranked lower in that gametype w/those same stats.
In the end I think what people are saying is the stats that are tracked in this game are not a good indicator of how to judge whether someone is good or not, so dont worry about them.
i have a pretty low kdr and spm but on the dom leaderboards have 100's more caps and defends than anyone else above me.
i also rock a really good w/l for dom
spm kdr means bugger all for obj games
Stats in this game are meaningless. Until they stop allowing idiots to kill farm in the objective games k/d means nothing. It takes no skill to run around the map away from the objective and pick off people who are PLAYING THE OBJECTIVE.
This also means w/l means nothing because someone may have a poor w/l due to idiot teammates sitting back going for kills and not caring if they win.
SPM also is meaningless since not all game types are equal.
Also, many people in this game have connection issues. Until that is resolved not everyone is on equal ground.
I still think K/D is very important in objective games. I can't tell you how many times I've played with people who play the objective but don't make an effort to win gun battles. They rush the objective (Domination/Hardpoint specifically) and get killed 4 or 5 times before they actually capture it. This leads to our team leading the match for the first 25% or so but then the other team starts calling in score streaks. Now because of teammates who are 5 kills and 26 deaths, the other team starts hammering us with lightning strikes, turrets, dragon fires, etc. I've lost plenty of matches due to the opposing team's score streaks. So even though someone may have 5 or 6 captures, their terrible KD leads to the other team being able to win the game.
SPM is hard to judge because there is a very wide adjustment say from HCTDM to Hardpoint. Mode based SPM and K/D is what matters. In HCTDM a VERY good SPM is around 200-225, while in HC CTF the lower side of SPM is around 225. All you get score for in TDM are kills, so if a game goes 10 minutes and a guy has 20 kills, its a 200 SPM.