I may be able to help you here actually :)
So you have your DA kdr which if you glance someone's weapon stats can be padded because medkits, same for kph. HSR can be too if you play like a total faggot with certain weapons and people do that too which is fine.
What you want to look at is their account stats per minute and per hour, its in the general information section. The hourly kph should tell you what you need to know, when cross compared with their weapon stats. Also damage done per hour and per minute shoiuld be postive values, kind of arbitrary at that level but it would be odd for these to be negative values. The other thing you want to check is in the infantry only domain, you want to check that kdr especially, for infantry guys. It tell you your Statistical infantry only kdr, which is seperate from your overall DA kdr. So your infantry only kdr factors out things like non sanctioned weapons and vehicles. For instance nivx's kdr is like 10 but his infantry only kdr is like 17. For infantry bashido players such as myself i prefer it. No in all instances but some.
Now what a lot of this won't count for or apply to a players who has improved, you will be able to see that in their weapons stats for certain weapons they did after say (new pc). You should be able to figure that out no problems or old and new account. Another site we use to measure player performane is a site called http://www.planetstats.net/, click the link. It tells you your kdr and spm over the last month of play as well as some arbitrary skill rank, It doesnt tell you much until you look at top teir but even then its arbitrary so it still doesnt really matter, and its dependant upon playstyle so i wouldn't read into that to much. It has some other account stats there as well to look at.
Planetstats.net also shows you you improvement or lack of for the month too when compared to your all time stats as a percentage. Here is a quere i made of some players in your outfit for you too lokk at, http://planetstats.net/axisbond,exocett,krack3r,pegsz,madmaukh,yodddd.
You can of course also do this with new applicants and their alts as well. Ok, so i hope that helped dude :) Have a good weekend.
Cheers, MikeHonchoYou