Stat’s are ranked by kills yes, the stat’s you see on the website and server (far right colum) are identical with the exception that the website does not keep a live update.
Individual game stat’s (who you see as a winner of the game) is ranked by Round wins, then kills, then money.
“SKILL” is currently just another value, you can short the stat’s page by skill if you wish but it’s not the official unit of measurment. This is because the skill value is not nessessarly respected as a accurate equation. Kills is the most un-bias (this is open to intepretation even by myself) value becuase as the saying goes “a kill is a kill”.