Luckily for Lee, he has both the talent factor and the relatability factor and both came out at just the right time. 

In terms of talent, Lee has the basics: intrinsic motivation, charisma, and musicality. He looks like he genuinely loves music, feels the music, and has the musical skills to express that. I didn't used to think he has much charisma, but he has steadily increased his charisma as the season has progressed. Lee also doesn't have any extreme features that may sour his overall impression. I think other contestants this season like Siobhan Magnus (who I was a big fan of!) may have alienated some voters by being a bit too "odd". 

Lee has also steadily been turning up the juice on just the factors that psychologists Rena Subotnik and Linda Jarvin identified through interviews with over 80 top music students are crucial to "elite" musical performance: self-promotion skills, having a good agent (in this case, the agent is Simon Cowell, who has been increasingly lending his support, even in song choice), capitalizing on strengths (e.g., selecting songs that highlight his best range, heightening his looks, etc.), overcoming self-doubt (this has been a major theme for Lee- he has increasingly and clearly been overcoming his self-doubts), exuding self-confidence (he has progressively and more clearly stated his intention and self-perceived ability to win), good social skills (he's been trying really hard to smile more), persevering through criticisms and defeats (he has humbly said that he appreciates the judges earlier criticisms and he has been working through them), and taking risks (he has been changing it up in terms of song choice). The congruence between the traits Lee has increasingly displayed across the season is strikingly similar to the traits that Subotnik and Jarvin argue become more important as elite musicians move up the ladder in their careers.

In terms of relatability, Lee's backstory is perfect. He never graduated high school. He worked as a paint salesman. He is the rebel with just a dream and a guitar. (Note: There may even be much more to the story than this, see this article. If true, I applaud the producers for not playing up that story.)

This backstory paints Lee as the underdog, which gratifies our deeply ingrained desire for justice. "We would admire an Idol who performed well and received a deserved positive outcome," notes Norman Feather, a psychologist at Flinders University in Australia. 

Lee also seems like a genuinely nice guy, which adds to the relatability factor. "We want the best man or woman to win—not just the best singer, but the best person," says Pamela Rutledge, Director of the Media Psychology Research Center. "Narratives are the way we make meaning out of life. Idol represents an archetypal narrative: the journey, the quest against all odds." Lee's story allows us to project our own hopes and dreams.

In one study, Social Psychologist Richard Smith and his colleagues gave college-age students stories to read from The National Enquirer. When students read stories about high-status celebrities suffering negative events, they reported feeling  high levels of emotional gratification. On the other hand, they reported liking stories about average people experiencing good fortune. "We aren't going to identify with celebrities," says Smith. "We're going to identify with someone from our state." 

Anyone out there who has failed in school or has felt like a failure but has kept dreams of being a rock star close to their heart will like Lee; Lee provides inspiration to quite a lot of people.

But perhaps the most important reason why Lee will win is because he has clearly shown growth. Lee's growth cycle has the perfect arc. His display of talent slowly increased, and I'm sure he hasn't even peeked yet. In fact, I predict that in the Finale we'll see a performance from Lee like we've never seen before. Even Lee's friend Brian Friedopfer thinks so: "I've seen him goofing off around us and he's belted out some crazy stuff. He hasn't done that yet. He's been pretty tame out there. So watch out, America!" he is quoted as saying in this article.

Lee's rate of growth also adds to perceptions of his deservedness and also contributes to the voters' feelings that they are in control of the outcome, playing a supporting role in the success of their favorite contestant. "We identify with people who try hard—especially when they become successful. We think, 'That could be me up there—if I had the talent'," says Norm Wiener, a sociologist at the State University of New York at Oswego. There is an interesting irony at play here. We want someone with talent but also someone who appears deserving of those talents.

Lee's growth cycle also dodged the hot button of intimidation. Psychologists Penelope Lockwood and Ziva Kunda at the University of Waterloo found that's it's a fine line between inspiration and deflation. They found that high achievers whose successes were relevant to the dreams of their participants and whose successes also seemed attainable, evoked inspiration. If the high achiever's success seemed too unobtainable, participants reported feeling deflated. Lee struck just the right balance here, slowly and steadily increasing displays of his talent at just the right rate. 

Finally, Lee is humble. This trait is key to winning American Idol as it in for anything in life. Not only does being humble increase likability, it diffuses the hot button of high status. Lee's level of humility is just right. He doesn't have too much confidence that would make him seem cocky and unappreciative of success, but he has steadily increased his confidence levels to the point where his belief in himself leads others to believe in him.