When Cardi B’s “Bodak Yellow” topped the US Hot 100 singles chart, Nicki Minaj tweeted her congratulations to the rapper. “Bardi, this is the only thing that matters!!!” she wrote, “Enjoy it.” Minaj has millions of fans, sells out arenas and sets various singles records – but somehow a number 1 is the only thing that matters. At first glance, it seems odd, even as a throwaway statement in a tweet. Charts are dull and mostly only of interest to people knee-deep in the industry. But it also makes sense when you peer closer: The US singles chart tallies every single song sale, stream and radio play in a seven-day period , accounting for the music tastes of nearly 330 million people, and boils it down into a rank. It is, theoretically, the most important chart in the world – nothing else can boast the Hot 100’s comprehensiveness or scale. In other words: this actually could be the only thing that matters.

Composer and pop music theorist Owen Pallett suggests that Martin’s writing style is completely by-the-books, which is why they have historically done so well. “[Martin’s songs are] a textbook adaptation of what makes a good melody,” says Pallett. “There are tonnes of little rules you learn in school. Max Martin always seems to follow them.” He continues: “Martin has a lot of secret ingredients, but one of them is this tendency to write melodies that kind of function as programming scripts,” he says. “They do a function, they’re not improvised on" – the function being, of course, the creation of that earworm sensation of not being able to get a song out of your head. Melodies are repeated over and over again, “so they’re branded on the listener’s ear.”

Last year, he made it very close with two songs: Taylor Swift’s “…Ready for It?” and Katy Perry’s “Chained to the Rhythm,” which both peaked at number 4 . For such pop heavyweights that high achievement is practically a disappointment. With only two top 10s to his name, 2017 was pretty much his worst year yet. On paper, 2017 should have been a cakewalk: he wrote nine songs for Taylor Swift’s Reputation , five for Katy Perry’s Witness and four for Pink’s Beautiful Trauma. In the past, Martin has created 14 of his number 1s and nine of his top 10s with those three artists. So why have Martin’s fortunes suddenly shifted? His music is, arguably, the same as it’s ever been – which might just be the problem.

Max Martin, the Swedish pop songwriter most famous for working with artists like the Backstreet Boys and Taylor Swift has 22 Hot 100 number 1s , all of which he attained post-1991 – the year when the chart stopped reflecting sales estimates and started counting every single sale and radio play. There have been roughly 360 number 1s since 1991, and Martin, with his 22, accounts for about six percent of that. A rare interview subject who doesn’t maintain a social media presence, Martin is pretty much an unknown quantity outside of the music industry. Except he’s not, really. You definitely know his work: since 2008, Martin has had number 1s every year . Even in his lowest performing year, 2013, he still had two. But not so in 2017.

The shift back towards hip-hop on the charts can be put down to a number of factors, but the key is streaming. While streaming numbers have factored into the Hot 100 chart since December 2014, the impact of that change is only slowly beginning to be seen. From March 2016 to March 2017, Spotify gained over 20 million new paid subscribers ; the broader growth of streaming services is thus being reflected in the charts. In 2013, when a list of the most torrented artists in the world was released, Billboard reported that piracy was decreasing due to streaming . With hip-hop and R&B artists disproportionately represented on that list, it would make sense that as more users migrate from ripping music to streaming, the charts will begin to show us more accurate representations of what people are listening to (though the Hot 100’s metric is meant to be changing). In the UK, streaming’s has less of an effect overall since it was folded into chart data in July 2014.

In the past year, the Billboard charts have started to swing towards hip-hop and R&B. Last year’s biggest songs weren’t analogues of “I Kissed A Girl” or “We Are Never Ever Getting Back Together”; they were rhythmic, lyric-heavy tracks like “Bodak Yellow” or “XO Tour Lif3” , the kind of songs that used to dominate the charts circa the mid-2000s. Even the songs that weren’t strictly hip-hop still leaned on rhythm and lyrics more than an outright pop pop song would. Ed Sheeran’s “Shape of You,” the most successful song of 2017 and Sheeran’s most successful song ever , coasted to number one off the back of its (quite questionable) dancehall-inspired beat, and it is telling that Sheeran had to make such a dramatic stylistic shift in order to gain that kind of success.

The era that Pallett is talking about – around the late 90s and early 2000s, when Britney and Backstreet Boys were in their commercial primes – was Martin’s first period of large-scale success. From about 1996 to the very early 2000s, Martin wrote a number of commercially successful hits (“Baby One More Time” and “It’s Gonna Be Me” among them) that established him as a pop savant. But somewhere around 2003, the tide slowly began to change. RnB and hip-hop began to dominate the singles charts again, and Martin’s output didn’t yield another number one until Katy Perry released “I Kissed A Girl”, which ushered in the writer’s second wave of significance.

“One of the reasons Backstreet Boys sounded so strong when they emerged, in my opinion, was because Mariah Carey was doing [songs] like ‘Fantasy’ all the time,” explains Pallett, “all ornament, all ad-libs, mega-overdubbed. The verses were wild and all over the place like hair flowing in the wind. They’re melodies painted with a brush, whereas Max Martin writes his with an architect’s pencil.”

Pallett suggests that a key difference between many of last year’s hits and most of Martin’s songs is that in Martin’s music, lyrics aren’t hugely important. You can see this most explicitly in the absurd grammar in the chorus of Ariana Grande’s “Break Free” – Grande sings: “now that I’ve become who I really are” rather than “really am” to service a rhyme. (You can see it too in the way that the verses of “I Want It That Way” don’t linguistically align with the chorus.) “‘Shape of You’ sticks around the same four notes and has short phrases – its primary function is the transmission of the words,” says Pallett. “[With] Martin’s melodies, the words are there, and they’re important, but they’re secondary to the shape of the melody.” This is antithetical to the composition of songs like “Bodak Yellow” or “Despacito”. In “Despacito”, words fly at a million kilometres a minute, while “Bodak Yellow” doesn’t even really have a melody; it is all lyrics.

You get the sense that Martin knows his typically Swedish style of pure-pop songwriting is going out of vogue and is adjusting to compensate, a phenomenon most obvious when looking at his work on Taylor Swift’s Reputation. Most of the nine tracks Martin produced for the album flirt with a facsimile of icy, unemotional trap or _Yeezus_-style maximalism. These songs are identifiably Martin, but with enough window dressing that they don’t sound too familiar. But listeners are savvy. Chart newbies like Cardi B or Migos have had better-performing singles than “...Ready For It?” by sheer virtue of the fact that their music is the real deal, as opposed to something dressed up as trap. If any of Swift’s Martin collaborations were to reach number 1, it’d likely be “End Game”, the album’s collaboration with juggernauts Ed Sheeran and Future, or “Delicate”, a trop-house number that, while still out of character for Swift, doesn’t seem as unnatural a fit as “…Ready For It?”

While Martin had an unusually low-key 2017, there’s nothing to say that his 2018 won’t be a return to form. Ariana Grande and Selena Gomez, two artists Martin has worked with in the past, are set to release albums this year, which could be the writer’s ride back to the top. The stars of Gomez and Grande have risen a good deal since they each last released albums (2015 and 2016, respectively), and while neither has ever had a number 1, 2018 could be the year – that is, if they even choose to work with Martin again. Increasingly, pop artists are choosing to work with newer, fresher writers like Jack Antonoff (who last year wrote on St Vincent’s MASSEDUCTION, Lorde’s Melodrama and Swift’s Reputation) , and Julia Michaels, the co-writer of Justin Bieber’s “Sorry” and many Selena Gomez singles. Michaels in particular, with her knack for writing deeply rhythmic vocal parts, seems to be in tune with pop’s current moment in the same way that Martin was in the early 2010s.

While unlikely, there’s a chance that Martin may be past his prime – a songwriter who can no longer tap into what listeners genuinely want. I doubt it, though; trends in pop are cyclical, and we could be seeing a resurgence of Martin’s pop traditionalism in a few years. He’s already learned how to pivot to trap, after all. In the meantime, it’s nice to see new faces reach the peak of the Hot 100. After all, this is the only thing that matters.