Grantland just published “Fifteen Years Later: Tom Cruise and Magnolia,” an excerpt from Amy Nicholson’s book Tom Cruise: Anatomy of an Actor. It’s fascinating. Here’s a bit about Paul Thomas Anderson, Tom Cruise and Tom Cruise’s giant commitment.

Cruise gives the role a fascinating combination of confidence and insecurity. He comes on like a gorilla — literally — stripping down naked in front of Gwenovier and beating his chest. The nudity was Anderson’s idea. Cruise hadn’t flashed his underwear since Risky Business, and hadn’t gone fully nude since All the Right Moves. (The glimpse of his pubic hair has since been edited out of Moves.) On the day of the shoot, Cruise started the scene simply sans shirt, exposure he was used to. Then Anderson asked him to take off his pants. “I said, ‘What?’” recalled Cruise. “He said, ‘Yeah, yeah, yeah. It’ll be funny.’” To Anderson’s glee, Cruise disrobed. Gushed the director, “He’s like, ‘What do you want me to do, do you want me to stand on my head, do you want me to do backflips? I’ll do it, I’ll do anything you want.’”

With his manhood a tabloid fixation, all eyes were on his crotch. And the bulge in his briefs was distractingly large. Given Anderson’s previous use of a prosthetic penis in Boogie Nights, the columnist Michael Musto of the Village Voice launched a crusade to find out if “the garden hose is 100 percent real meat.” “I don’t know whether to be insulted or feel complimented,” joked Cruise, while Anderson was more definitive: “Tom Cruise is the biggest movie star in the world. Are you kidding? Of course he’s got the world’s biggest cock.” (Naturally, Cruise looked into a lawsuit against Musto.)

The excerpt goes into the specifics of Tom Cruise’s T.J. Mackey character, inspired by “seduction Svengali Ross Jeffries, a former paralegal” — the pickup artist motivational speaker archetype, an unsettling concept in today’s post-Elliot Rodger world. Like here, after 3:00 — targeting, chick friends, Denise the Piece, all that is there — fifteen years ago.

P.T. Anderson lifted some of Jeffries’ speeches verbatim, but apparently, Cruise contributed some really key elements.

“What Tom Cruise doesn’t know is that he was playing a character that I created,” explained Jeffries. “I’m not Ross Jeffries — that’s a persona I put on in my seminars.” But Jeffries underestimates Cruise’s intelligent reading of T.J. Mackey. Cruise knew that Mackey knew his act is artificial. His smooth moves have the practiced look of a performer who’s done them hundreds of times in a hundred different hotel convention centers. Mackey is a self-made construct who comes to life only under the spotlight. Who naturally strides around with their arms akimbo and fists clenched to their hips? Underscoring Mackey’s control over his artificial persona, after the one-two disasters of his interview with Gwenovier and the news of [his] father’s imminent death, Cruise shows us how he switches back into character onstage as easily as putting on a mask.

However, during his final lecture (“How to fake like you are nice and caring” — ironic, as Mackey really fakes being a jerk), it’s hard to tell if — or when — Mackey strays off script. “Men are shit!” he yells, “We do horrible, heinous, terrible things!” That sounds like Mackey, but Cruise’s movements get crisper and angrier until the film audience alone — his in-person audience never suspects — spot the seething hate and pain. Cruise’s jaw twitches, his voice builds, and when he yells, “I will not apologize for who I am,” Cruise makes it deliberately hard to tell if he’s talking to the crowd or himself. Mackey claims he can control a woman’s mind, but can he even control his own emotions?

Tom Cruise rules.