Almost three years ago, with the “Relapse” project in the works, I got a call from a Detroit Free Press reporter about the prospects for an Eminem comeback. It wasn’t hard to be hopeful on the rapper’s behalf—fellow Detroiter Kid Rock had just proven for the second time, with “All Summer Long,” that nobody was more than one great song away from recapturing CHR’s attention.

The harder question was what sort of record Eminem needed to make. It was easy to say that Eminem was repeating himself a little in the mid-to-late ’00s. Eminem’s straight ahead girls-and-partying appearance on Akon’s “Smack That” seemed like the obvious route, but it didn’t seem like the best use of his creativity. (And on the subsequent “Crack A Bottle,” it didn’t prove to be the easy comeback, either.) I’m very sure, however, that I didn’t suggest a longish story-song ballad about abusive relationships.

It’s just over a year since Eminem & Rihanna’s “Love The Way You Lie” came out. And in my listening to Top 40 radio this week, it’s as unavoidable as any of the candidates for the Summer Song of 2011. If I listen to two CHR stations consecutively, I can pretty much count on hearing it twice in one sitting.

It’s interesting now to look back on the impact of one song over a year’s time. Here are a few of the song’s achievements over the last year:

It cemented 2010 as the “Year of the Comeback”: In 2003, both Eminem and Train were forces at contemporary radio. You would have more likely bought Eminem stock back then, given where music was going at the time. Instead, both acts’ fortunes declined for a while. And both came back last year to win over an audience of 15-year-olds and their 39-year-old moms, neither of whom had been the exact right age when Eminem became (in every way) the new Rolling Stones for a few years in 2000-03.

It changed the notion of an “adult record”: While a few very Hot ACs tried to acknowledge the early '00s success of “Lose Yourself,” Eminem at the height of his initial stardom had been the effective dividing line between Mainstream and Adult Top 40. But “Love The Way You Lie” appeared first on Radio-Info’s hybrid “25+ Hits” chart of Adult and Mainstream Top 40 stations, then made the Hot AC chart outright. The biggest Hip-Hop crossovers now get enough Adult Top 40 airplay to regularly appear on both charts. Because after Eminem made the Hot AC chart, it was hard to say what else could not.

It defied the notion of a “summer song”: The last two summers have seen a glut of uptempo party jams that are clearly inspired by “I Gotta Feeling.” This is not such a song, but its gravity doesn’t seem to be an issue this summer either.

It helped restore two careers: Singing the hook of a song inspired by her own abusive relationship was the unlikely final springboard to Rihanna’s ubiquity of the last year. Somehow, it allowed her to take final control of the story in the way that “Russian Roulette” had not.

It helped create a new Hip-Hop template: You can’t say that “Love The Way You Lie” restored Hip-Hop’s luster: Lil Wayne, Drake, and Nicki Minaj did that. And Hip-Hop still isn’t restored to its “only contemporary music that matters” status of a decade ago. But Eminem and Skylar Grey did provide two other rap artists with an unlikely semi-ballad template for comeback songs. And the Bruno Mars-produced “Lighters” by Eminem’s current Bad Meets Evil project has a similar feel, as well.

It reinforced the power of the lyric: Every now and then on my other job doing music research, somebody will suggest that any Hip-Hop song is the beneficiary of a “false positive” reading from listeners who like the (often sampled) hook but hate the rest of the song. The hook here was definitely a selling point, and it’s disappointing that the sung-only Rihanna follow-up wasn’t better. But you either have to believe that listeners completely overlooked the rest of a difficult-to-swallow four-and-a-half minute story song with no happy ending, or accept they at least appreciated its substance. Even in a Country format that now includes “Country Girl (Shake It For Me),” there’s still a perception of story songs and substantive lyrics. So it’s nice that Top 40 has some of its own in an era of fist-pumping party jams and jackhammer repetition.

It proves that long can be strong: Okay, four-and-a-half minutes is not “Stairway To Heaven” or “Paradise By The Dashboard Light,” but programmers have been wondering recently about the PPM strength of longer songs. As in most other PPM-inspired discussions, this one depends on the content as well. As Radiocrunch’s Anthony Acampora points out, “Sweet Home Alabama” and “November Rain” still have pretty good MScores as well. As important, while some stations have edited the song for content, there’s not much you can take out without losing something, unlike, say, “Say” by John Mayer.

Thoughts about Eminem, “Love The Way You Lie,” rap ballads or current product? Please leave a comment.