I could be reading too much into it, but it seems to me like guys coming back from injury rehab are getting safer assignments to start.
Flores hasn't been particularly good this spring from what I have seen so perhaps the same applies.
I would guess Fulmer gets the last pen spot and the bench will be McCann, Mendick, Cuthbert, and Engel, with Engel getting the first shot at platooning with Mazara.