The thing is, we won't need to "spell" two starters, at the same time, so there really is no need to have Eaton and Monasterio on the 26. We already have IKF and 4 OF'ers.
Our biggest bench need other than back up Catcher is filled by IKF. The next need is for a decent PH'er, and who looks like the highest need PH players?
1. Wong
2. Mayer
3. Rafaela (?)
4. Durbin (?)
Masa can PH for any of these guys, even the LH'd Mayer. I'd rather have Masa as the #13 than duplicated value. Now, if someone gets hurt, then all this could change, depending on who it is. If it's an OF'er, Masa's role expands to fill the DH slot, nearly FT. If it's an infielder, then maybe we look to make a chance, but we can also just fill the infield IL'd player with Sogard, Gasper, Romero or Eaton.