The fallacy of that thought though is that it wouldn't have helped any at all. OKC was playing small ball, so Ibaka would have been the only big out there. Sure he would have challenged shots at the rim, but instead of Gino and Parker getting into the paint for scores, they just would simply make Ibaka commit and then pass to Duncan for the score.
What happened in the 4th wasn't about talent or skill. What happened was all about execution and effort. OKC just got schooled on what execution and effort look like, not unlike the Jazz teams of the 90s used to do to the Spurs.
Once the Spurs hit some outside shots, the painted opened up like a car pool lane, and the Spurs made all the right plays and all the correct passes, like they've been doing all season.