Bargnani was a guy I was thinking about for that Ibaka, Melo and Rubio mix.
Big enough and a strong enough post defender to handle the centers Ibaka cannot. Ibaka's high level team defense, shot-blocking and rebounding helping Bargnani's weak points. Bargnani spreading the floor for Melo to drive and post + for Rubio's dribble penetration and pick and roll game.
I'm not completely sold on it (because of Bargnani's flaws) but the fit there intrigues me.