Payoff ratio
The average winning trade divided by the average losing trade.
Payoff ratio measures how large the typical win is compared with the typical loss, independent of how often each happens. A ratio below 1 means the average loss is larger than the average win, so the win rate has to compensate.
A low payoff ratio combined with a high win rate is worth a second look: it often means small, frequent wins are funded by rare, large losses.