If they can extend Grienke's contract, this is a great trade. If they can't, it's still pretty good. Losing Cain hurts, I think he had the chance to develop into a pretty damn good player, maybe even as a star defensively. I wasn't too high on Escobar; he's a liability at the plate, and has some makeup concerns. Jeffress has an electric arm, but I doubt he'll ever be anything other than a reliever. Odorizzi could develop into a stud, but if you can lock up Grienke, that concern would be mitigated by a fantastic 1-2-3 for years to come.
I've got to give Melvin some credit; he's finally building a pitching staff, and moving the team away from, what I thought, was a team much better suited to play in the AL. The Brewers are now a legitimate contender for the division title.