Bannon is a fine player himself. He picked up the game at seven and became an accomplished amateur at Kirkistown Castle Golf Club, a links 20 miles south of Bangor, hard against the Irish Sea. He turned pro in 1981 and went on to win more than 20 titles on the Irish Region Tour, a club-pro circuit. His biggest win would have been the 1998 Irish PGA Championship had he not lost in a playoff to 27-year-old Padraig Harrington. "Three-putted the 17th green to lose it," Bannon says.
Teaching was Bannon's other love, and in the early days he plied his trade as an assistant at Holywood, where he became friendly with Gerry and Rosie McIlroy. Gerry was a scratch player, but the buzz surrounded the McIlroy's only child, Rory, who by the age of nine was performing trick shots on national television. It was around this time, McIlroy says, that "Michael took charge of my golf swing."
Young Rors loved the process. Bannon would video his swing on an analog camera, and then they'd deconstruct it together, with Bannon marking up his small TV screen with an erasable marker. "Even in the wintertime, Rory would come down once a month, or once every two weeks," Bannon says. "He always pushed himself. He would have said, 'I think I need to go see Michael. I think I need to do this.' It wasn't like he had to come. He didn't need to do that. And even today it's the same way." Working toward a common goal bonded teacher and student; Bannon became like family. "He knows Rory's whole personality, his golf game, inside out," Gerry says. "I would even say Michael knows Rory as well as I do."
(Related Story: Rory's trainer reveals how his client packed on muscle)
Rory was a sponge. "If I told him something, he'd come back in a week or two, and he'd have it fixed," Bannon says. Rory also possessed the ability to self-correct, a skill he still calls upon. Through two rounds at the BMW Championship in Indiana last September, McIlroy was blocking everything. So he hunkered down on the range for 30 minutes and hit nothing but draws to reacquire the feeling of moving the ball right to left. On the weekend, McIlroy conducted a driving clinic and won by two. "You can get coached all you want," McIlroy says, "but you have to make your golf swing your own, and Michael has let me do that."
Through good times and bad. During a lull earlier this year, McIlroy weathered allegations that he was focusing too much on his tennis-star girlfriend, Caroline Wozniacki, and not enough on his game. "It had nothing to do with Caroline," Bannon says, laughing; it was more a case of McIlroy taking the club too far inside on his takeaway -- and Bannon has the video to prove it.
"You see what I mean?" he says back in his office. On the monitor is a split-screen image that shows McIlroy on the range at Royal Lytham next to McIlroy two months later at TPC Boston. "You see the club is more in behind the hands slightly, whereas at the minute it's more in line. The difference now is very marked in terms of how he's coming into the ball. It's still a wee bit inside, but that's okay. It's a very strong attack."
Bannon loves his videos, but he's not an overly technical teacher. He's more concerned about how McIlroy "feels" when the club is in certain positions. "He'll always write that down," McIlroy says. "Like, 'Okay, in January 2010, this is how you felt like you got it into that position. So try to feel that again.' It's all about reference points and keeping track and keeping a log on everything. That's what we've done throughout my career."
Only time will tell if their system will continue to work and if McIlroy will continue to buy into it. Tiger Woods is on his third coach. Padraig Harrington blew up his swing after winning three majors. Which leads one to wonder if McIlroy ever feels tempted to try something new.
"Not at all," he says firmly. "I don't think there are any secrets out there. I know when I play my best golf, I'm going to have a chance to win tournaments. And I think I'm getting better because when I'm not playing my best golf, I still have chances to win. I think that's just growing up and knowing my swing a bit more and knowing my tendencies."
And knowing not to mess with a good thing. As Bannon says, "Rory had a great swing at 14, 15, 16. We don't actually change that swing, we just check to see if it's in the right position."
As he says this, his monitor displays his star pupil frozen in midswing. Bannon looks up at the screen and smiles.
"You know you don't go changin' that there," he says. "What would you want to be changin'?"
This article originally appeared in the December 2012 issue of Golf Magazine, on newstands now. Click here to subscribe to Golf Magazine and to learn about Golf Magazine All Access.