Right, because there were players available that guaranteed that? It's the 28th pick for christ sakes. It's very unlikely to find a player who can come in and contribute right away. There are exceptions but there were none this year. I get that fans think they know more than top level scouting teams that spend months and months watching these players, I mean I get it, a youtube video of highlights trumps actual dedicated scouting and putting effort into analyzing players.
As you said, the Spurs are in a win now mode, and a late first round pick isn't winning you les now. But cap space and signing the right FA's or making the right trades will.