I don't think it is about rest as much as about health. Kepler has made several awkward swings where he is definitely in pain, same for Cron, and probably also for Cruz. Replacing them today with healthier players makes sense for today and for the postseason IMHO. It would be great if Cave and/or Gonzalez are ready to go because those two are big league players who will certainly be on a postseason roster and they probably need plate appearances to get ready. I don't relish the thought of seeing Miller, LaMarre or Wade get at-bats, but whatever it takes to get Kepler, Cron and Cruz as close to 100% as they can be is what is needed.