I like Lewis, but he isn't that great of an MLB player. Probably won't be. Never an elite hitter. Can't play center or SS any more. His chances of being a bust are greater than him being a star, imo. Miranda has at least been the best hitter (sort of out of nowhere) in our farm system before. And even he snuck up on people.
Trading guys who can play for questionable return, then keeping guys with higher trade value who can't play is a recipe for getting worse.