More than that, I think Barnes served his role with the Kings. They needed a steady vet with playoff (and championship) experience to help them finally reach the postseason. HB won't have a shortage of suitors since he works equally well as a reliable 4th or 5th option for a contending team or as a mentor for a young, upcoming team. But I think for the Kings to take the next step, replacing Barnes as a starter is the most clear route to help shore up some weaknesses.
I wouldn't be upset if he were re-signed and the Kings essentially ran it back, but there's an opportunity to get a better fit that also matches the Fox/Sabonis/Murrary timeline better.
One issue with Barnes and Murray as the starting forwards is that neither is a strong rebounder. I think Murray will continue to improve in this area, but last year HB averaged 4.9 rpg per 36 minutes and Keegan was only slightly better at 5.6 rpg per 36. Neither of them are rim protectors, but Barnes had moments of 1-on-1 creation that we hope Keegan develops. Which is why his struggles in the playoffs were so glaring. Outside of Fox and Monk, the Kings lack a guy who can get his own shot when needed.
So who represents a clear upgrade?
Pure statistical analysis (and per 36 numbers especially) never tell the full story because it depends on who a guy shares the court with, his role, the team system etc. But just for fun, I'll list last season's numbers for some guys we've discussed as Barnes replacements and you tell me who you think fits best.
Here are the per 36 numbers I'll focus on, starting with HB.
Harrison Barnes 37.4% 3P% (4.8 attempts), 4.9 rpg, 1.7 apg, 0.1 bpg, 0.8 spg, 52.2% FTr, 63.2% TS%, 17.1 USG, -1.5 DBPM
Possible replacements:
Player A: 37.2% 3P% (2.4 attempts), 8.4 rpg, 0.6 bpg, 1.6 spg 36.3% FTr, 70.3% TS%, 12.6% USG, +2.0 DBPM
Player B: 40.1% 3P% (5.8 attempts), 4.5 rpg, 0.8 bpg, 0.8 spg, 37.5% FTr, 60.5% TS%, 22.8% USG, -1.4 DBPM
Player C: 33.3% 3P% (7.7 attempts), 7.4 rpg, 0.5 bpg, 0.6 spg, 20.8% FTr, 54.4% TS%, 27.9% USG, -1.5 DBPM
Player D: 36.9% 3P% (6.9 attempts), 8.7 rpg, 0.8 bpg, 0.9 spg 30.4% FTr, 60.7% TS%, 18.1% USG, -0.9 DBPM
Player E: 30.5% 3P% (2.1 attempts), 8.2 rpg, 0.9 bpg, 1.2 spg, 22.8% FTr, 59.2% TS%, 13.2% USG, +2.6 DBPM
Player F: 35.8% 3P% (4.0 attempts), 5.2 rpg, 0.8 bpg, 1.4 spg, 20.6% FTr, 57.1%, TS%, 17.8% USG, +0.6 DBPM
Added:
Player G: 34.6% 3P% (6.2 attempts), 9.6 rpg, 1.5 bpg, 1.2 spg, 22.0% FTr, 61.7%, TS%, 24.8% USG, +0.8 DBPM
Player H: 39.5% 3P% (5.1 attempts), 6.4 rpg, 0.5 bpg, 0.7 spg, 25.6% FTr, 60.5%, TS%, 13.1% USG, +0.7 DBPM
Player I: 37.2% 3P% (7.3 attempts), 5.6 rpg, 0.4 bpg, 1.6 spg, 28.9% FTr, 61.0%, TS%, 21.1% USG, +0.6 DBPM
Without looking up who is who and just based on stats, who would you pick?