big match performer

what is the actual definiton of big match performer?

some said the player that perform in one of the final he involved?

some said the player that perform in almost every matches except certain match?

some said the player that perform in almost every k.o matches until the final?

some said what ever his beloved player did in the certain key match?

in my definition, the player should at least perform majority of the key matches to be so called big match performer, may be in 70-80% of it, not just 1 or 2 games from 10 attempt