Obviously you’re not rostering all those players in the playoffs, that’s what’s known as a depth chart
And yes defense is ultimately much more random in short bursts like a playoff series. You could play a seven game series and have zero opportunities to make a play considered a game changer. But you have to hit once every nine times and if all your warz come from being elite defensively and a noodle with the bat your opportunity to impact the game decreases significantly