I don't judge people by their numbers, but when you look at how they play in the game, and by their SPM, KD, W/L, Accuracy, class setups, total score, days played, etc.....they all have to point to a semi reliable conclusion.
I say semi reliable becuase there was that Envy dude, with the 130-0 game....he's a TDM player who goes into Domination and runs stacking, cycling streaks, and camps balls like a cuntypussy.
He's a trash player who would rage quit if he came accross a semi-conscious opposing team.
For the most part, you can tell a bit about how someone plays by thier numbers.
Doens't make it right, doesn't make it accurate....but it's a general feel that's in the same ballpark as the reality.