I mean really, where would you improve this staff? Bullpen?
Depth, since you never know who will regress or who will be injured.
Can't expect Kluber to be Cy Young winner again.
Carrasco can't be as nearly perfect as he was for the last six weeks.
House is very likely to be another one of those lefties who has a good first season and never another one [see Sowers, Laffey, Huff, et al.]
I think Bauer is going to take a step up and be much better than a fifth starter.
Salazar needs to show he can stay at the top of his game for a full season.
As current depth starters:
Tomlin can pitch in the majors, but he's no better than a 5th starter. Too many home runs.
McAllister looks he's a reliever, not a starter.
The only other depth is from Cloyd and Brewer. I'd like another lefty.
AA's best arm Cody Anderson had an ERA way up in the 5.00+ range.