Hypothetical.
You are up 2-0 in a best of 5, heading to the road. Your rotation has an Ace, a 1b, a solid 2, and a solid 3. Do you leave your 4th starter as next in line to potentially pitch in a game 4 and save your Ace for a game 5, or do you set your ace up for game 4, and have your 1b/solid 3 go in game 5?