This type of trade proposal makes no sense. If you're giving away the best player in a trade then you're losing that trade. The only circumstances in which trades like this should be considered is if 1) the star player is demanding a trade, and this is the best package you can get back, or 2) the team is rebuilding, in which you are willing to take on a combination of prospects, bad contracts, and/or future 1st rounders. Brown is not demanding a trade, and Boston is not rebuilding.
Do not trade stars for the sake of trading them. You need to receive equivalent value for it to make sense - a star player that is hopefully a better fit for the team.