Battles
The number of battles on an account or a vehicle, and the sample size every other statistic has to be read against.
Also known as battle count, games played, fights.
Battles is the denominator of everything. Damage per game, win rate and every rating are averages over it, so the count is what says whether an average is a measurement or a coincidence.
Useful thresholds: below about 100 battles on a vehicle the numbers are noise, a few hundred show a tendency, and a thousand or more is stable. Leaderboards apply a minimum for this reason, otherwise the top of every board would be accounts with a handful of lucky games.
Battle count also carries history. An account's lifetime figures include the battles played while learning the game, which is the entire argument for looking at a recent window instead.