The Spurs Might Have the Best Offer for the Celtics
San Antonio would be giving up a decent bit of draft capital, though it wouldn’t totally leverage its future. Unlike bonafide stars who have been traded for a treasure trove of draft picks in recent years, Brown is only a one-time All-Star. A pair of picks (one of which was acquired from Chicago in San Antonio’s trade for Young in the offseason), a swap, and a second could sweeten the deal for Boston.
The Spurs have a handful of young players who they could mix and match into a prospective deal—though it would only make sense to trade if they retain enough of their own talent to keep pushing closer to the playoffs again. Boston would likely look at different packages, but depending on what’s out there, this package or a similar one from San Antonio might be the best they’d get.
Ultimately, this entire conversation is more a reflection of the state of the Spurs. Stuck somewhere on the spectrum between the draft lottery and the play-in tournament, San Antonio's roster is too talented to tank and not good enough to make a serious push in the postseason. They need to keep their eyes peeled and pounce on a trade when the right opportunity reveals itself.
If the Celtics really wanted to separate Brown and Tatum—which they probably shouldn’t, quite frankly—then the Spurs should be very interested.