Well, the FO has only so much to work with. We have been "cursed" with being one of the top 4 teams in the league for nearly 20 years. So all the draft picks are in the late rounds. Sure there have been a few gems, but only Tony, Manu and probably Kawhi have turned out to be more than just role players. In addition to that, the Spurs have had to give away draft picks so they can acquire free agents. And because of the three stars we've had, there hasn't been a lot of money to go around. So those free agents have to be guys at the tail end of their career or specialty players. AND NOW, the Spurs are just good enough to get to the playoffs and compete, no longer good enough to get over the hump. So they are STILL stuck in the later rounds of the draft and with over the hill free agents.
So yeah, it seems like the FO fault, but I guarantee that OKC will be in the same boat at some point. Such is the circle of life in the NBA. Hakuna Matata motherf###er.