Only problem with the wait-and-see approach is you have to set the roster before the series. If you're gonna roster a potential 4th starter and use him in the bullpen unless game 1 proves you'll want him to start Game 4, then that's fine. I could see using Irvin or Flaherty that way, not really Gibson. Maybe Means depending on how built up his stamina is.
Yes that's how I would approach it. And Flaherty is currently the guy I'd lean to. I don't really like any of our #4 options but at least Flaherty has some playoff experience (a lot more than Gibson).