It's so weird that Boston pivoted from Brogdon for KP to Smart for KP. If they found a way to swap Brogdon, Gallinari and Muscala for KP, even for 1-2 FRPs to Washington, they would be in much better position. Losing Smart is going to hurt the team, as he was their best defender and instigator. His offense leaves a lot to be desired, but you would think that he would get fewer shots with KP. I'm guessing this moves Brogdon to starting PG, and the team defense will rely more on Tatum and Brown to play D.
Brogdon's injury issues will likely continue, and they will be paying him 22.5m the next 2 years for about 50 games a season. It's going to be even worse if he's recovering from elbow surgery this offseason. That risk is a huge gamble over Smart who has missed some games, but seems to be more reliable over his career.
I do think Memphis made out well here. Getting Smart to replace Tyus Jones as the backup PG is pretty good. He has more years of control at a reasonable rate, and he could easily slot into the starting lineup over Bane or when they want to go small. He will add more toughness to their defense, and help with countering some of the offense focused teams like Phoenix. I think the issue with Memphis right now is, who replaces Dillon Brooks at SF? They are over the cap with the current roster at 144m, so I guess they need an MLE guy to fill that gap.