Not liking/loving this deal is not simply a matter of emotions. Marcus had a down year, but was the DPOY the previous season, when the team's defense carried them to within two wins of a title.
He was also their most consistent player when it came to playing hard, something we've all lambasted this team for. Marcus certainly had bad games (maddening ones), but it was rarely if ever due to lack of effort. The Celtics too often lack urgency, but that's not true of Marcus.
And since he clearly wasn't healthy last year, are we trading him at his lowest value or getting out before everyone realizes this is who he is now? That's what none of us know just yet. So no, condescending comments aside, this is not simply an issue of "emotions versus analytics." (As though emotion doesn't count on a basketball court. As though we haven't seen this team submarined by a lack of emotion over and over again.)
I trust Brad, but I would have wanted a lot more for healthy Marcus, and if he's back to his regular form next year we're going to miss what he brought to this team. The good always outweighed the bad with him, even if the bad drove us nuts.