The Rockets are really building a solid core. But we still need a veteran PG to mentor Amen and run the starting lineup whilst he adjust to the NBA. We also need a Centre for either the staring lineup or bench depending on how high you rate Sengun. Particularly a rim protecting Centre that can potentially space the floor would be a bonus. This trade does both, Claxton is a very good defender and can space the floor a little, plus Mills can be that veteran for half a year or even a year for Amen. Brooklyn do this as they get a nice young player in KMJ and their frp for next year back.