Sano didn't play 1st base for even an inning. He played RF and 3b. I really don't have any idea what you're talking about here. For 2017, it's one fallback at DH/1B, not 3 or 4. Sano isn't going to play 1st base, he might DH some, although to me it makes the most sense to keep him at 3rd base every day. I could live with a day or two at DH for rest, but he needs reps at 3rd, not DH. Plouffe isn't here. Keeping Mauer, Park, and Vargas gives you a rotation you can use to have the platoon advantage at 1st and DH every day, gives you injury backup which will inevitably happen to at least one of those three, and gives the manager a viable pinch hitting option on the bench every day. I don't think any of Mauer/Park/Vargas are going to be assets playing every day, none of them will likely hit enough. But a three way platoon at least gives you the chance of ending up minimizing their weaknesses and maximizing their strengths. I also haven't given up on Park, he was a really, really good player in Korea and I think there's a great chance he'll end up a decent to good one here, although he might end up a lefty masher.