Yes, and as a result of making a concerted effort to limit free throws, points in the paint, and 3 pointers, they allowed an abnormal amount of wide open midrange shots. They're an average defensive team that in order to limit one part of a team's offense needs to concede another part of a team's offense. They aren't a good enough defensive team to limit OKC's interior scoring and free throws as well as they did while also being able to contest their midrange shots.
The poor defenses they played against didn't dedicate so much to stopping OKC's interior scoring hence they didn't give OKC as many wide open mid range shots. Once again, you're kidding yourself if you think Ibaka saw as many open looks on a regular basis during the regular season as he did against the Spurs.
Teams taking "inefficient shots" wasn't remotely the reason why San Antonio had so much regular season success. They had regular season success with an elite offense and mediocre defense. Once again, they surrendered a shooting percentage HIGHER than the league average. In other words, they allowed more efficient shots than the average NBA team. Yes, that worked in the regular season, but the "You might shoot well but we'll shoot even better" strategy doesn't work in the playoffs.