trading a starter for the sake of trading one isn't a case of addition by subtraction.
the tigers are a strong team with both smyly and porcello on the staff. in that case smyly. i hope, goes to the pen. especially true with an all righty rotation.
the tigers do not have to make a trade at all. they will be stuck with peralta at short but they are still the strongest team in the ALC. once we get into the post season, we need to sort that out though.
everything that DD says though is to further his goal of improving the team by trade.