Double albums can be fearless declarations of self-indulgence, an idea dump for a band looking to expand its boundaries, give the secondary members a few chances to songwrite, or share that gestating song cycle about warring clans of magical elves with the world. The Red Hot Chili Peppers don't seem to be likely candidates for any of the above, having spent a two-decade career trafficking in progressively diluted funk songs about California, sex, and having sex in California. Then again, they've given their record the preposterous pseudo-Latin title of Stadium Arcadium (what's next, a music review book called Thesaurus Musicarum?), so maybe the shirtophobic quartet is ready to let their art-rock flag fly.

Probably for the best, that's not the case; through two-plus hours of music, the emphasis here is on the Stadium. Like many of their peers from the heady peak of alternative rock-- your Grohls, Cornells, and Billie Joes-- the Peppers have eased into a comfortable life traveling down the middle of the road. Kiedis, Flea, & co. can even stake a truly rightful claim to the territory now christened Adult Album Alternative, having practically induced labor on the genre with the mega-hit "Under the Bridge" and their subsequent string of ever-so-slightly askew mid-tempo pop. Fitting examples abound on Stadium Arcadium, catchy tunes that will ensure a long tenure for the album at the front of the store. The band's sin, however, is one of self-denial: If the Red Hot Chili Peppers have pretty much mastered a marketable style, why bludgeon us with an unwieldy and inconsistent approach for 1/12th of a day, nagged by an annoying tendency to detour through affirmations of their technical talent and loyalty to funk-rock?

It could've been worse, as the sessions that led to Stadium Arcadium reportedly yielded enough material for a triple album. So the band has shown some ability to self-edit, but not enough to save the record from typical double-album bloat, the islands of good tracks floating amidst the should-a-been B-sides. Conveniently-- or perhaps subconsciously-- the set is still front-loaded, with the first disc containing most of the highlights, like the expertly paced sunset anthem of the title track or the one-peak-after-another rave-up of "Torture Me".

But sprinkled throughout the first disc, and coming to a head in the second, are products of the band's compulsive need to tip the light-bulb hat to their younger selves, most notably half-baked funk tracks "Hump De Bump" and "Warlocks". Whereas poor production values and drug-fueled exuberance once excused their George Clinton worship, 20 years on, in Rick Rubin's sterile environment, the band sounds like they're in jamband training camp, filling in all the empty spaces with blippityblap reminders of Flea's virtuosity and John Frusciante's desire to use every effects pedal ever invented (potentially the primary motivation for making this a double album).

Isolated to the occasional compulsory workout, these excesses could be ignored, but when they slip into the over-long outros of straightforward soon-to-be-singles, the band's lack of perspective is obvious. Rubin, producing his fifth consecutive RHCP release, appears unwilling or unable to push the band into any kind of challenging territory, settling for inserting a great treated-drum breakdown in the middle of "Readymade" that he'll probably mine the next time Jay-Z rings him up. Brief moments where the band takes on a new identity, like the Fleetwood Mac-style finale of "Wet Sand", are fleeting, while other experiments (the spoken-word of "Death of a Martian", the bizarre background vocals of "Animal Bar") simply derail right as soon as they leave the station.

Maybe the Mac are an appropriate guidepost for the Chili Peppers, potential guides for how to sublimate a once-renowned rhythm section into slick California contempo-pop-- hell, they even made a similarly uneven double album! But keeping one foot in the funk of their origins and becoming mired in muso leanings is a ball and chain for the band's current incarnation as radio-pop darlings, a period that has now lasted twice as long as their goofball early days. By trying to incorporate all these personas, Stadium Arcadium can't help but grow as distended as the name suggests, revealing a band too proud to merely play the game they've already solved or use the added space to risk a less worn path.