Max and Stras are dominant and you fully expect 7 innings if not more from them in the postseason. Gio and Roark on the other hand...I can see a much quicker hook with them and then playing a bullpen matchup game. I'd be happy with 5 strong innings of 2 runs or less from them. I'd take 3 runs or less in 5 innings.
Strasburg has gone 5 innings in one playoff start.
You're going to lose if you expect any of your SP to go more than 6 innings in the playoffs.