Good points, but I'm expecting our strong starting pitching to go deeper than 5 2/3 innings, and even if they don't, I think just about every pen arm could pitch in all 5 games without experiencing fatigue, unless one game goes 16 innings.
I doubt Poyner makes the roster. He was held down in AAA while many of our current RP'ers were struggling.
If we go with 12 pitchers, I'm guessing it's a long man like Wright, Pom, Johnson of Velazquez, so we can handle a 16 inning game or a couple games where the starter exits early.
If we're using 10 pitchers in back-to-back games, chances are it doesn't matter who our 25th man is.