Murray, when healthy, is arguably an equal value to Brown, but he isn't healthy and who knows when he'd play again.
At one point I proposed something like Brown for Murray and MPJ. Boston takes on Denver's damaged goods for a chance at real contention in a couple of seasons while Denver goes for it this year in a fairly wide open season. To make the dollars work, someone else from Boston has to be included so given the trade, Schroder makes sense. So Brown and Schroder for Murray and MPJ. I'd do that trade. It would basically be throwing in the towel this year for Boston, but given where the team currently is, that might not be a bad thing.
So post trade
Boston would potentially have a very nice trio for years to come in Tatum, Murray, Porter and Denver really goes for a title this year with a starting 5 of Jokic, Brown, Gordon, Barton, Schroder and still has Brown next to Jokic long term.
To do this, Boston would have to feel comfortable that Murray and Porter will be able to heal from their current injuries, so it would be a big risk, but it is the type of trade that I think makes good sense for both teams.