The Reds either need to extend Castillo or trade him. Holding him into his free agency makes no sense. Draft pick isn’t enough to compensate for his loss.
Luis is a good extension candidate because he’s a good GABP pitcher. Strikeouts and ground balls. Fits the ballpark much better than Tyler Mahle.
I could go either way, extend him or trade him for value. Depends on what deal Reds can make in either case.