Whit has a better profile to be a good starter, but I, too hate messing with something that has worked.
Having a one-two long relief punch from Whit & Houck would do wonders for the short RP'ers on the staff, as well as allowing Cora to yank SP'ers early, if needed.
Had we kept them both firmly in their pen roles, all year, we'd still have a lot of choices as SP'ers:
Sale, Kluber, Pivetta, Paxton
Bello, Crawford, Wink
Mata, Walter, Murphy