When Anthony Kiedis told Variety about the unspoken, unwritten law of Red Hot Chili Peppers, one “where anything goes, anything is welcome,” the vocalist could’ve been talking up the gloriously manic mess of “Unlimited Love” (the “anything goes” bit), and the return of guitarist-composer John Frusciante (the “anything welcome” part) to the RHCP fold.

What is most welcome when it comes to the Peppers’ sliding-scale-quality catalog is focus, a cohesiveness given to Kiedis, bassist Flea and drummer Chad Smith almost exclusively by the solid, fancifully flighty melodies and impressionistic guitar work of Frusciante. Bringing back the Chili Peppers’ most masterful producer, Rick Rubin, for the 17-song expanse of “Unlimited Love” is an additional exercise in finessed focus and wild-eyed frenzy.

A quick game of compare/contrast is proof of Frusicante’s prowess and power. There for “Mother’s Milk” (1989) and the epic, emotional “Blood Sugar Sex Magik” (1991), but gone for “One Hot Minute” (1995). There for the breadth of “Californication” (1999), “By the Way” (2002) and “Stadium Arcadium” (2006), but gone for the darkly nuanced likes of “I’m With You” (2011) and “The Getaway” (2016).

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Though the group’s two most recent albums before “Unlimited Love” were among its most tonic and even touching works, there was little from either album that really stuck to the ribs. And if there’s anything quantifiable about what makes a great Peppers album greater, it’s its ability to shock, awe, roll and rock you into riffing submission with skronky jams, melancholy metallicism, weirdly tender balladry, Kiedis’ ruminative cheetah-chatter, and a handful of seemingly unwieldy, ultimately warm melodies.

I loved “The Getaway” wholeheartedly, but there was nothing I could sing from it and sway to, over and over upon first listen, as I did the surefire stadium-fave “Black Summer,” the first single from “Unlimited Love.” How could you not love a fluidly cinematic, gi-hugic Peppers melody with Frusciante doing his signature, rich background vocals below Kiedis auditioning an Irish pirate accent?

It is this balance of experimentalism and familiarity, of the tentative and the trusted, that makes “Unlimited Love” utterly unstoppable and unlike anything you’re likely to hear this year. That means making angular horn sections and fret-less bass lines into something salient, even poppy, on “Aquatic Mouth Dance,” placed beside downright elegant piano ballads such as “Not the One.” That means cowboys, freedom and a lost America through the high-plains-drifting “The Great Apes” programmed next to the slithery R&B of “It’s Only Natural,” followed by the equally snaky soul of “She’s a Lover,” muted cowbell and all. Even the electro-pop-meets-brush-denim country of “Bastards of Light” somehow makes sense within the “Unlimited Love” playlist.

It’s probably tedious to say that a band of 40 years (or half of this band, at least) sounds in sync, but this current quartet is wearily and cheerily lived-in, with Frusciante slipping into his old roles still weirdly and melodically – his specialties – but comfortably and with a mature edge. On “Unlimited Love,” you can hear the impressionist’s mastery of Frusciante in his spacy math jazz (“Aquatic Mouth Dance”) and softly spun Frippertronics (“Not the One”), but he also wolfs his way into genuinely heroic rock riffing.

The Townshend-ish crackle of “The Great Apes” and its full blown Who twin “These Are the Ways” (big points to Smith and Flea for playing Moon and Entwhistle on the latter track), the psychedelic Robert Smith-like flight of “Black Summer,” the Flea-dueling plunk of “Here Ever After” — these all show off Frusciante’s six-string talents in a manner that RHCP neo-classics “Blood Sugar Sex Magik” and “Californication” only portended.

Going from soft to raging, from Doors-esque cabaret to last-chance powerdrive on “The Heavy Wing” (with Frusciante singing the chorus), is downright majestic. Even the simple way that his galloping strum and f-hole twang cozy up to a quietly swaggering Kiedis on the dumbly titled “White Braids & Pillow Chair” is gorgeous.

Maybe, finally, Frusciante’s restless soul has settled and he gets the hint that part of his Red Hot job is to rock, hard. And that the other part of the gig is to frame Kiedis’s Beat Gen poetry and oddball references (woman as traffic jam, free roaming monkeys, hitting someone with a Guggenheim) into something even more handsome than the singer manages on his own.

And whether it’s the intimate swagger of “Veronica” or the homey clarity of “Let ‘Em Cry,” Kiedis, the vocalist, has found his job description’s pocket by reveling in maturity, trafficking in mood and basking in his baritone’s multiple shifts from clipped to crooning.

And even the pirate stuff works if you let it.

At 17 tracks, perfection is futile. Wah-wahs and raps on “Poster Child”? The absolutely frightening idea that an “aquatic mouth dance is waiting for you”? Eh. Then again, perfection has never been the Red Hot Chili Peppers’ strong suit. Neither has obviousness. That’s fine. They wouldn’t know what to do with either.

What better way, then, to end “Unlimited Love” than with an unlimitedly lovely and spare, muzzy, slow song, “Tangelo,” one with awkwardly poetic lyrics (“the smell of your hello, the smell of tangelo…I know-oh-oh”), a gentle flicker of guitar and an unforgettable melody that pronounces at its start, “Ain’t this life grand?”

To welcome back two old friends in Frusciante and Rubin — and for Kiedis to find new voices amidst vintage whines, for the guitars to saunter jazzily and riff ragingly, and for the band to find some of the most memorable melodies of its long career — really is the best kind of grandiosity.