For discretionary traders, the most important stat to know after drawdown is max adverse excursion. That is the amount of red ink a trade can absorb before the probabilities shift against you. It's probably the single most valuable thing you can discover via backtesting.
Daytraders can achieve very high win rates, but the achilles heel will always be the big loser. If you avoid the big losers, you can make good money as a trader. The first step to avoiding them is to know when a trade has gone sour. It sounds easy but when your money is on the line, it's one of the hardest things in life to do.