You act like I said "why haven't they signed James, Wade or Bosh?". All I'm saying is that this notion that they're going to out-smart everyone and get some quality veteran for cheap is probably not realistic.
If they're serious about winning the championship next season and not just being as cheap as possible while maintaining a sliver of hope at competing, then they should be aggressive and pushing to get something done. It might even take a hint of creativity and not just sitting around waiting, thinking "we're the Spurs, someone credible, who's flying under the radar will come to us later in the summer for cheap and we'll make out like bandits". Maybe they are being aggressive, I'm not ruling out the possibility. But with the amount of information flying around and them figuring so little into it, I'm inclined to believe they're not.
The Timberwolves sign Pekovic immediately and they're still messing around with Splitter, even though they should have been prepared well in advance to sign him the instant free agency opened. They knew it was probably going to take the full MLE, so just offer it and move on to the next order of business. They're more than likely not going to get him for around $4 million and they desperately need him if they have designs on winning the championship next season. There is no realistic alternative that makes that feasible. Why risk alienating him? He can make more staying in Europe and he might just stay if they don't give him what he wants and what he's worth.
This "we're smarter than everyone else and we're the Spurs, so they'll come to us and on our terms" nonsense has to go. That carried weight in Duncan's prime. Now, they're not some prime destination, they're just a team struggling to maintain relevancy.