Idk, but this did seem to come out of nowhere completely, like almost everything that's happened to us this offseason
I think DA views Kemba as a perfect fit on this team, and he is still an All-Star caliber player, a Top-25 talent in the league + probably Top 6-7 PG in the whole league. He definitely has more accolades than guys like say, Vucevic. He probably thinks Kemba offers the highest potential of all realistically available targets, as a guy who can legitimately impact games and winning as well.
Not at all saying Vucevic is a scrub btw, but he would command like near-max himself and while he would fit a glaring need, the truth is I don't view him as a guy who can have a major impact in the games that count (including playoffs). That's just my opinion.