Coming to this thread late (Friday morning). Completely concur with @MGX that it is too soon to make judgments on Banda and particularly SWR.
I read that Banda's velo is down considerably (2-3 mph) and that is a red flag. He was used a lot by the Dodgers last year, but fairly well shielded from facing elite RH hitters. With three left handers in the 'pen and no shut down right handers, Banda has faced more neutral opportunities. If he continues to struggle in his next several appearances, I wouldn't be surprised if he was cut loose or finds his way on the Injured List.
Woods Richardson would seem to be the definition of a back-of-the-rotation starter. He doesn't have plus velocity or movement, so his margin for error is pretty small. He has provided value for the Twins in each of the last two years and is still a minimum salary guy who is quite young (25). I doubt anyone else in the organization could step in and be consistently better. He also seems to be a good student of the game and gets a lot out of his ability.
Among the position players, the current "darlings" would be Gray and Kreidler. Gray is 30 and had 122 plate appearances coming into this year. So far, he's hit surprisingly well, but I'm skeptical that he will be able to sustain that performance. He does seem to be this year's version of Kody Clemens and my thought is that he continues to hit and Clemens doesn't, that Gray could assume some or all of Kody's current role.
Kreidler is undoubtably a very good defensive player on the left side of the infield or in the outfield. However, in about 200 plate appearances, he is a .141 hitter. If he can hit just a little bit, he can help this team. The record says that is unlikely. He's homered twice which make his OPS skyrocket, but it is tough to believe that he can hold his own against big league pitching.
Finally, Matt Wallner had hit another dry spell. With it being so early in the season, his numbers went from pretty good to substandard in a short time. He keeps striking out at a Gallo-like pace. I don't know how much runway the new manager has for him, but a straight up switch for either Alan Roden or Emmanuel Rodriguez probably isn't out of the question if the struggle lasts another week. Roden had quite a long snag at St. Paul, but has hit well this week, while Emma has been the most consistent of the Twins' top prospects at St. Paul.