Basically you look at the position players entering the season:
Starters: Vasquez, Moreland, Nunez, Bogaerts, Devers, Benintendi, Bradley, Betts, Ramirez
Bench Catcher: Leon
So if you start with a 12 or 13 man pitching staff ... you are basically down to 2 or 3 players. If we assume a FA signing of some kind (JD, Lomo, whomever) that gets you down to 1 or 2.
So you are looking at, what Brentz, Holt, Castillo, Swihart for 2 spots maybe?