I get the concern on Sale, but he still had great numbers even with reduced velocity. He's shown he can be a pitcher not a thrower.
One has to think that once Sale is traded, Quintana might be on the block. I mean why stop there, if you are in rebuild mode.
What has not been discussed is who else is part of these packages. If it's just Moncada for Sale, then I'd be leaning towards doing it, but they might want JBJ too. I might give Swihart, Moncada, Owens, Hembree and Pablo (and cash) for Sale and Frazier. The money paid on Pablo would be just enough to keep us under the luxury limit, if we traded Buch for a low cost RP'er or two. I think Sale + Frazier = $13.5M, so that balances out Buch's contract. We could pay $10M of Pablo's $19M a year and still be under the limit. That might not be enough to a team looking to rebuild and talking on Pablo's problems, but it's probably close.