The reason why the Spurs are so poor is not because of the draft, but because every single player that gets any playing time is under 23 years old and most of them under 20 and barely have any experience. They have little notion of how to win certain aspects of the game, they're getting so much wrong and the whole team is having to learn together.
When you have strong vets, this is completely different. Instead of five guys making mistakes you may have one, and the others can cover for that player in that situation.
When you have five mistake makers on the floor at all times, it's incredibly hard to get it all worked out. Add to the mix sort of pausing everything to figure one anic player out, and the fact that the roster is missing parts anyway.
Last year at this time the guys balling out were Sandro and Julian, both of whom have fallen completely off.
The team might do well to pick up strong vets in FA but it's unlikely to happen. A trade or two might happen. But ultimately the improvement will and has to largely come internally and by building collective and individual knowledge.