But plumbing the appeal of Dwayne Johnson the actor requires setting the size of the package aside for a moment, the better to zero in on subtleties: The expressiveness of those unnaturally mobile eyebrows or the way, either in character or during the course of an on-camera interview, he almost seems to blush when he makes a self-deprecating joke, as if he were wary of calling too much attention to himself. Johnson is so good-natured that even when he's not wearing a smile, his facial muscles carry the ghost of one. Maybe that's part of his charm as a performer: For such a big lug of a guy, his star quality is of the quiet sort. [. . .] But they haven't tarnished Johnson either. Just as his body has been trained and disciplined to sustain all sorts of physical abuse in the ring (he retired from pro wrestling in 2004), so is Johnson, as an actor, fully willing to endure all kinds of humiliation, ribbing and teasing emasculation — and always with a smile. (Stephanie Zacharek,...