Kings of Leon did it all in reverse. Contrary to many indie bands, their album trajectory moved upwards, with their previous two albums showing both musical improvement and maturation from their 2003 debut, “Youth & Young Manhood.” These sons (and nephew) of an evangelist preacher converted to rock ’n roll and all the vices that the lifestyle entails. While this aura fueled their early success, their last album, “Because of the Times,” helped them to be accepted as a respected band, not just an interesting story.

Yet their latest work, “Only by the Night,” finds the quartet stalling — even taking a step back. The lackluster and generic sound has neither the originality of their early works nor the good song writing of “Because of the Times.”

After three albums, it is obvious that K.O.L. can no longer rely on Southern charm or the unintelligible, yet unique drawl of lead singer Caleb Followill. On “Only by the Night,” there is nothing to hide the mediocrity of the songs.

To the band’s credit, the album’s opener, “Closer,” sets the bar too high, with all subsequent songs failing to match its atmospheric intensity. The song opens with a recurring eerie guitar riff and Nathan Followill’s heavy drumbeat; a delayed ringing guitar — reminiscent of the Edge’s clean, ethereal sound — enters to create a syncopated tension between the two guitars. As Caleb sings the chorus a final time, “And it’s coming closer,” the song climaxes, with a short but sweet energetic romp. Sadly, this 30-second outro sees the band rocking the hardest of any point on the entire album.

This does not bode well for the Kings of Leon, who claimed that “Only by the Night” was going to “rock harder” than any past album. There must be some misunderstanding. Compared with much of K.O.L.’s past work, “Only by the Night” can barely be considered pop-rock — only “rocking harder” than Bryan Adams.

The band seems lackadaisical throughout. On the sappy and dragging “Use Somebody,” a build-up sets the stage for … a disinterested eighth-note guitar solo that only meanders through scales? This is not the same Matthew Followill who, on the Kings’ last album, executed a masterful solo on “On Call” and the simple yet majestic guitar part of “Arizona.” And despite an interesting Strokes-influenced riff on “Sex on Fire,” the catchy and overly-simplistic chorus leaves a lot to be desired.

Lyrically, the album finds Caleb trading the mature themes of “Because of the Times” for a mixture of trite love songs and testosterone-laden sex pleas. “Only by the Night”’s lyrical highpoint? The story of a teenager’s night out in Manhattan: “We’re gonna fuel the fire / We’re gonna stoke it up / We’re gonna sip this wine / And pass the cup.” What did you expect considering Caleb claimed that his lyrics were influenced by pain-killers after a fistfight with his brother Nathan?

Whether the creative spark be substance-aided or not, it is obvious that Kings of Leon needs some inspiration. “Only by the Night” proves that they have run out of ideas, or maybe have sold their Southern-garage soul.