I don't think it was truly Duffey's to lose, especially if you are including such apparently weak factors as "keeping one more reliever" from the uninspiring group of Tonkin, Kintzler, O'Rourke, etc. Molitor said it would take something "fairly significant" for him not to be in the rotation, and while Duffey hasn't performed that great pending today's results, it's pretty clear that nothing "fairly significant" or unexpected has happened. I think the talk of Duffey having a spot, for him to lose, was pretty much just lip-service, maybe to make him feel more comfortable, reward him for his 2015 contributions, and/or to motivate Nolasco and Milone. They essentially kept May in the rotation hunt for the same purposes, it wouldn't be shocking if they did the same for Duffey one rung up the ladder.