Actually 3 man..
Cueto, Arroyo, Latos, Cueto, Arroyo
4 man:
Cueto, Arroyo, Latos, Homer, Cueto
You get Arroyo pitching instead of Homer.
But I get your point.. if you are going with a 3 man rotation, it kind of makes sense for the first round to have Latos go #2... However, the benefit of the 3 man rotation as shown.. If the first round goes to 5 games, you start the second round with Latos (assuming the Reds survive game 5 of round 1).
Also, if the Reds go to a 3 man rotation, they have the option of starting Homer in game 5 as a "surprise'. That idea makes some sense. Dusty might like the opposition not seeing Arroyo twice. If Homer is rested and ready to go, he might go in game 5.