Davey has forgotten more about baseball than any of us will ever know, but he is not above question. His 7th inning manuevers were curious to say the least starting with removing our most dominant pitcher after on 89 pitches.
Zimmermann has never pitched more than 161 innings, and if we make it to October we'll need him to be effective. Using the pen to make starters outings low stress makes sense for the whole season.
Most critics of Davey, and yes I'm including you and SF in that category, tend to focus on the situation at hand as opposed to the full season / 25 man roster big picture. Davey is clearly focused on the big picture and makes decisions accordingly.