That's looking at only part of the picture. What does the HAC say? Like I said, once I'm suspicious I exhaust all my resources before becoming "unsuspicious", including talking to the player themselves. You'd be surprised how much info you can get from a seemingly innocent conversation. Eventually, they're gonna have to perform in front of me. I once raised three people on one team from watching them in one round of a tournament, even though two of the three lost. There are aspects of a persons game that you just can't measure on paper, and are hard to hide if you know what you're looking for. I guess I'm saying if you rely only on wins and losses, or other "measurables", you're missing some of your best resources.
I've always said that the best handicapping system is one person who knows everyone and rates them accordingly. But that doesn't scale, so you rely on a hybrid system of measurements where you can and local knowledge where your measurements fail (and they WILL fail at times, no matter what you're measuring). The key is to know your people well enough to know where your measurements might be failing. That's the "secret sauce" that makes any large-scale rating system successful. Again, no trade secrets there, just paying attention. That's a big part of my job. Anyone who doesn't pay attention isn't doing their job. Do I think it's infallible? Absolutely not, but until I hear of one that is, my opinion remains.