I think people are overestimating the cost of Mayo here. At best right now he is a FV 55 prospect given the serious concerns about his defensive position (and if we avoid some of the prospect inflation MLB pipeline tends to grade out). That of course is still a great prospect! A FV 55 position prospect is worth $46 million. Misiorowski is a FV 55 pitching prospect which has a value of $34 million. That is the main piece. A second piece would be Lara and then maybe Quintana. So one top prospect, one good prospect and one decent prospect. Two top prospects is too much.
You could also replace Misiorowski with Frelick who is probably the most replaceable player on the MLB roster since he is playing out of position.