No argument there--I'd agree that Swanigan is a superior rebounder, mostly due to his "motor", which is honestly another reason why he probably should come off the bench. "High motor" guys are generally better suited for quick-stint roles, so that their effectiveness can be maximized over the time that they're on the floor. It's arguable that Swanigan--despite his legendary work ethic--could see his effectiveness begin to tail off later in the game if he's going "all-out" for every loose ball for 25-30 minutes per game, especially later in the season, when the grind of the NBA schedule begins to wear on him. We might be better off--at least early in his career--with limiting him to 15-20 mpg, in two shifts per game (each of which span a quarter break), allowing him to go "full Caleb" for the entirety of his minutes.
All speculation, of course, but it's a thought.