@Kung Fu Wang sums it up better than I can. Keeping at opponent at a distance in a fight uses fuel/energy. The smaller your "tank" the less time you have to devote to anything, whether it be running, delaying, attacking, defending etc. As such there are times where delaying is not the preferred tactic. If I have less endurance BUT better technique and/or more strength I am better served going "all in" in the hopes I overwhelm him in short order. If I delay it can actually play into his hands because I either tire and can't delay anymore, and he still has fuel in the tank to destroy me OR he just presses the attack beyond my ability to delay and again, he wins.
Of course if you have a choice one should not face an opponent with more endurance BUT if forced to fight someone with more endurance in a self defense situation, the element of shock/blitz is your best friend. It's not only what I see as a core tenent of WC but also Krav Maga and more modern fighting systems that are designed around self defense/combatives.