Couple things:
Dunn has finally made the move to 1B. Long overdue. This was not going to happen with the Reds.
Dunn has improved as a hitter this year, after a several seasons of treading water as a Red. As noted on the telecasts, he's gone to a heavier bat and is using the whole field better. It is likely this would not have happened with the Reds, for whatever reason.
Fantasizing about Dunn still in a Reds uniform? Not the same guy you're looking at now....