Oh, how quickly they grow up.

It seems like just yesterday that the Red Hot Chili Peppers were sex-crazed, L.A drug fiends prancing around the stage with socks on their members. However, at a time when bands like the Beastie Boys and R.E.M. are too busy chatting up the Dalai Lama and assaulting flight attendants to release decent albums, the Peppers have quietly evolved into the elder statesmen of alternative rock.

Unfortunately for the record buying public, the band won’t let anyone forget their newfound maturity. Their newest release “By the Way” exchanges their trademark funk-rock hybrid in favor of a more mellow, melodic approach to pop music that comes off as, well, boring.

This is not to say that change in itself is bad for rock bands. Hell, if it weren’t for change, Paul McCartney would still be onstage singing “Can’t Buy Me Love” at age 60. Oh wait —

The natural progression after the restrained genius of the band’s 1999 comeback album “Californication,” “By the Way” regrettably comes off as flat and uninteresting. Gone are the energy and shake-your-ass hooks that have powered every other Chili Peppers release; in their place are 16 songs built around the same chord structure and vocal line. As Anthony Kiedis himself sings in “Throw Away Your Television” (incidentally one of the album’s more abysmal tracks): “It’s a repeat of a story told / It’s a repeat and it’s getting old.”

Strangely enough, it is Kiedis that is for once the star of a Red Hot Chili Peppers record. Finally clean after years of drug abuse, his voice sounds stronger than ever. The demons that haunted him for years are now also fodder for some of his most personal lyrics this side of “Under the Bridge.” While his words have lost some of their mystery and humor, Kiedis seems to have finally come into his own as a lyricist.

While Kiedis is improving, his bandmates are slacking off on “By the Way.” The usually monstrous rhythm section of bassist Flea and drummer Chad Smith is unusually tame. For the first time, Flea has abandoned his innovative bass-slapping style for a more subdued picking sound. At the same time, Smith appears to have forgotten his role as one of the most badass drummers in rock, barely tapping the skins in most of these newer songs.

Ironically, guitarist John Frusciante, while responsible for much of this new sonic direction, seems conspicuously absent on the record. After a triumphant, fiery return on “Californication,” he seems to be more interested in creating the fleeting layers of sound that pepper his solo releases than in recording a decent guitar line.

“By the Way” is not a total loss, though. The title track, released as the first single, is a fine piece of pop-rock. Together with songs like “Midnight,” it represents the direction the album could have gone. Instead, fans are stuck for the most part with rubbish like “Cabron,” a tune which sounds like a cover of a bad Latin folk song by a bad mariachi band (assuming, of course, that there is such a thing as a good mariachi band).

While change can be a great thing for any band, it just doesn’t seem to be the Peppers’ bag on “By the Way.” Then again, it took the band 10 years and four albums before they refined their sound and released their groundbreaking masterwork “Blood Sugar Sex Magik.” We can only hope that “By the Way” is such a stepping-stone to another great album.