He'll go with eight relievers, likely with Grimmer as the 8th (seeing as how he is completely out of options -- he either is in the bullpen, traded or DFA'ed), so that takes care of keeping Zags at AAA. And with the addition of Darvish, Caratini gets to soak up AB's at AAA and act as trade bait, while Gimenez takes up the backup catcher duties on the big league club.
Your bench will be Zobrist, LaStella, Happ and Gimenez most days, except for those days when Darvish starts, or when we're facing a LHP. And I betcha that, even on days when Yu starts, Willson may end up playing left, or first -- depending on who has the hotter bat, etc.
I can still see a trade window, even before the season starts, that could include people like Montgomery, Caratini and even (if he has any trade value) Zobrist. So, the 25-man is likely pretty well patted into shape, barring such a trade, but the 40-man could still see some adjustments before the season starts.
Here's a question -- at what point does Bourjos look to be a better bench-sitter than LaStella? Tommy gives you a left-handed bat and spells infielders with spot starts, but Bourjos gives you an almost-daily defensive sub in late innings for Schwarbs (or whoever starts in left on any given day). And Happ, when he isn't spot-starting, gives you that left-handed situational bat off the bench, as well. I wonder if Bourjos won't take the bench spot that Tommy is currently keeping warm...?