Based on what? He played a fine Game 7 and an important role in their championship last year. So where is this coming from?
He just turned 24. He would immediately become our best 2-way player. He's a piece to build a championship around.
Folks seem to be removed from reality here. There is this assumption that we are going to land a franchise-caliber player -- as if it's a foregone conclusion, just a matter of time. Realistically, that is not likely to happen. Even if it does, you need to surround that guy with players like Barnes to compete at the highest level.
If you can't attract that hypothetical superstar in FA, then use that option to collect Barnes-type players that will play important roles in that championship run (if it happens in this decade).
He can defend 4 positions and shoots 40% from 3. He has championship pedigree -- knows what it takes to win and was asked to perform at the highest level for 2 years now, very early in his career.
He can get you a bucket when you need it, too. If you didn't notice, they'd readily go to Barnes on switches (e.g., Irving) and he would execute with a post-up and jumper in the lane. He also finishes in transition.
I can't fathom why we wouldn't overpay for a guy like Barnes right now. Our best option, imo, is to build through drafts (e.g., try to nab Okafor and Dunn/Brown this year), sign Barnes, and make use of AB/Crowder/Smart.
If Smart could return anything in a trade we would be incredibly fortunate, but his value is so much lower than what folks assume here. We are going to need to part with AB and/or Crowder and/or IT, and as much as people dislike the thought and assume our timetable is sooner than later, that's the honest truth. If Ainge doesn't make these moves, I will honestly be surprised.