The return of "Glee"  to the small screen naturally brings the return of the "Glee" cast to the Billboard Hot 100 , as well as an extension of the troupe's record for most entries in the chart's history.
The Fox ensemble sends three songs onto the Hot 100 from the series' Sept. 20 third-season premiere: "It's Not Unusual" (No. 65), a remake of Tom Jones ' first Hot 100 hit (No. 10) from 1965; "You Can't Stop the Beat" (No. 67), from the musical "Hairspray"; and, "We Got the Beat" (No. 83), which spent three weeks at No. 2 for the Go-Go's  in 1982.
With the bows, the "Glee" student singers create more space between themselves and Elvis Presley  for the most charted titles in the Hot 100's archives. The cast has tallied 159 chart entries, ahead of runner-up Presley's 108 (with his career having predated the Hot 100's Aug. 4, 1958, inception).
While the "Glee" ensemble is at the head of the class for most Hot 100 visits, are the act's grades slipping, however, when it comes to their chart fortunes?
The cast's top-charting song this week ("Unusual") bows at No. 65 on the strength of 40,000 downloads sold, according to Nielsen SoundScan.
In all, five "Glee" tracks debuted a year ago this week, all between Nos. 21 and 51, totaling sales of 409,000. This week, the download sales of the three debuting "Glee" tracks sold approximately one-quarter that amount (106,000).
Two more season premiere singles even just missed this week's Hot 100 cut: "Ding Dong the Witch Is Dead" and "Anything Goes/Anything You Can Do" each sold 21,000 and enter at Nos. 2 and 3, respectively, on the Hot 100's Bubbling Under  chart. (The five season-opening downloads sold 149,000).
What could be behind the comparatively diminished interest in new "Glee" music this season as compared to last year?
Let's brainstorm some possibilities. (Eyes on the board, spit out that gum and no starting your own show choir).
Music selection: Based on this season's start , "Glee" is offering more Broadway and less mainstream pop music.
Last season opened with the hip-hop sounds of "Empire State of Mind," as well as covers of then-recent dance/pop hits "Telephone" (Lady Gaga  and Beyonce ) and "Billionaire" (Travie McCoy ). The following week, "Glee" paid tribute to Britney Spears , with five Spears songs from the episode subsequently reaching the Hot 100.
This season's first two episodes, however, have featured selections from the likes of "Hairspray" and, this week, "West Side Story" (with "Somewhere" featuring Broadway veteran Idina Menzel). In "Unusual" and "We Got the Beat," the pop radio remakes have recalled not now, but 1965 and 1982.
The show's penchant for show tunes stems from "Glee" creator Ryan Murphy, who, approximating the role of a McKinley High music professor, told Billboard sister publication the Hollywood Reporter  earlier this year that "a lot of that stuff isn't taught. Or, the young audience is not exposed to it."
While such a musical menu enriches a young audience's musical palette, it can also make for a tougher path to Hot 100 success.
The youthful viewers that can most relate to the "Glee" characters are likely less familiar with decades-old songs, especially those that never received widespread radio play. Thus, they may be less inclined to purchase those songs digitally.
Ratings: The third-season "Glee" opener was down 32 percent in audience compared to last fall's premiere, although it still drew a solid 8.9 million viewers. The Sept. 20 debut of the quirky Zooey Deschanel comedy "New Girl" following "Glee" logged an even higher total (10 million) than its lead-in.
Perhaps the novelty of (the heavily-promoted) "New Girl" plays into a possible "Glee" glut: after two years ("Glee' premiered May 19, 2009), viewers, and, thus, music consumers, overexposed to "Glee" in its multi-media forms may be less stimulated by each new element of the series' product line.
The season premiere's ratings dip was even seemingly forecasted just a month earlier when "Glee: the 3D Concert Movie" opened to a mere $5.7 million at the U.S. box office. (The film has grossed $11.8 million total, hardly a mark worth pinning on the refrigerator).
A decrease in viewers, naturally, translates to fewer potential Gleeks downloading the series' musical souvenirs.
Second(-season) guessing: Behind the "Glee" ratings slip? Industry insiders and the blogosphere tend to point to a second season shorter on the more focused storytelling and character development of the series' first season. The show's sophomore season also splintered the cast, with the main New Directions glee club sharing time - and song selections - with Darren Criss ' Warblers.
Still, Fox is counting on "Glee" to remain a programming cornerstone.
"I think, frankly, some of (the backlash) was inevitable," Fox entertainment president Kevin Reilly theorized in an exclusive Q&A with THR . "When you are burning that hot on anything, sooner or later there's going to be the other side of it.
"There were a lot of things (that 'Glee') tried last season, some of which worked fantastically, others that felt like a little bit of a dead end or a dropped ball. But, what we've heard consistently is: 'I love the core characters. Can we just get back to them?' That's what you're going to see this season."
Clearly, "Glee" has stormed the Hot 100 like no other act, taking advantage of a loyal viewership and the digital era to produce multiple chart entries week after week in-season. The cast's music having toppled the King of Rock and Roll's long-standing record for most Hot 100 hits in less than two years reinforces the series' chart clout, as do its 11 consecutive top 10 albums on the Billboard 200, including three No. 1s.
Combined, "Glee" has sold 26.7 million downloads and 6.1 million albums, according to SoundScan.
Taking music choices, the series' ratings and plot arcs into account, what will the future impact of "Glee" be on Billboard charts?
- Chart Beat