Any locked up player they want to trade will not have positive trade value...or they would not want to trade them away. We are already seeing that with Olson and Murphy. So yes, the roster is inflexible in the sense that dumping declining players becomes impossible without attaching even more resources to them. And that defeats the whole point of signing them to a below market deal in the first place.
Having said that, I agree with unloading Murphy and going with a Baldwin/TDA platoon. I would also try to unload Soler so the roster doesn't have 2 DHs. How will that be achieved? No idea, but AA seems to be able to do things like trade the extra overpaid DH for an overpaid bench SS, so at least the overpaid player is at a position of need on the roster.
Then I would probably go with Kelenic/Laureano in LF, and bring in legit bench options for SS and OF. Do whatever BP arms they like, and the annual pulling a SP out of a hat trick.
That's assuming they want to reset the tax penalties and have very little money to spend. If they are going with another $275M payroll the options are nearly endless.