If Pleks is gone, who's your 1st line centre?You trade Pleks for basically the same player, then why bother trading him? You're not going to find a cheaper center that can replace him.
Of course Galchenyuk can play center, but not when you have DD as your 2nd line center and Eller as your 3rd. And no, DD can't play wing.
Thats why most people here want DD gone. Because it would've been easily Pleks-Eller-Galchenyuk as your centers if he's gone.
we can ask who is this teams #1 center even with Plekanec on it