I don't "love" Russell and people are correct to point out his negatives.I don't think it's love so much as realism, if the Nets are shooting for Durant/Irving/DAJ then they can't match an opening bell offer to Russell. I think everyone agrees that Brogdon is better in the abstract, but the Bucks are 100% certain to match, meaning a sign & trade would be their only shot at landing him. Russell? If they match they can't just trade him wherever for value, it wrecks their summer plans. And as a first max it's always tradeable down the line when they get an upgrade.
That said, he has only played four seasons in the NBA, the first two of which were in a suboptimal situation for a young player, and is just 23. Recent data suggests he is improving at least a bit.
More to the point, his flaws make him potentially attainable for Boston and his relative youth suggests that there could be some upside, especially in the right system. Atkinson got something out of him last year and I think Stevens may be able to build upon that.
Russell isn't a Kyrie replacement but he has some potential to give a team scoring while his physical skills, at least, suggest he could be a better defender.
If Boston weren't cap constrained, I would expect them to look elsewhere but Russell may offer some upside at a discounted price.