Back in the '90s, when Fat Joe was an East Coast underdog, he had the makings of an irresistible force. But six albums into his career, the 34-year-old rapper seems more like an immovable object.

It didn't have to be this way for the loud, proud and profane Puerto Rican-Cuban native of the Bronx. He's about 80 pounds lighter, he's coming off a huge hit -- 2004's "Lean Back" with his Terror Squad sidekicks -- and he's also waging a low-intensity feud with 50 Cent.

Despite all those potential sources of momentum, Joe's latest CD, "All or Nothing," is mostly dead weight. "I'm out / I swear after this disc I will quit," he says on "Does Anybody Know," adding, "It's hard when you're the only one supplyin' the wealth." A suburban dad at the dinner table has more pathos.

Even the singsongy "My FoFo," the answer to 50 Cent's dis track "Piggy Bank," is more about worn-out tough-guy postures than the delivery of actual venom. Borrowing the melody from the "Flintstones" theme, Joe calls 50 "the fakest thug you ever seen" and musters plenty of bluster.

But in the media, Joe has already issued his caveats: "I would have preferred for 50 not to dis me, me not to dis him, and we'd be perfectly fine," he told the New York Daily News. "I'm really not impressed by the rap battle thing."

That kind of honesty can be sorely missing in hip-hop's larger hype machine, but in Joe's case, it's the kind of white flag that comes before eternal irrelevancy. Even the beats on "All or Nothing" generally seem to cater to his desire for retirement -- they amount to a short-term investment portfolio. "Get It Poppin'," with its cutesy Scott Storch-produced groove and Nelly cameo, is already making cash on the airwaves; "So Hot," with R. Kelly lending a few sugary sex rhymes, is equally engineered to generate liquid assets; and "Everybody Get Up," with its patently futuristic Timbaland thump, is ultimately risk-free.

With all three of those songs, Joe commits the hip-hop sin of sounding too content. Street rap's greatest modern-day mouthpieces -- Jay-Z, Nas, Biggie Smalls, Tupac Shakur and so on -- all have forced mediocre material into the marketplace. But Joe lacks their charisma, even at his most playful. In his hands, the pop hustle has an extra whiff of unspoken cynicism, as if he knew only so much work was necessary to get "All or Nothing" moving off the shelves.

The big man brings even more mediocrity to the tracks where he plays up his 'hood-hardened "Joey Crack" persona. The two-part "Temptation" suite is a soulless collection of gangsterisms, and "Safe 2 Say (The Incredible)," despite some high-octane guitar and organ samples courtesy of Swizz Beatz, offers the same kind of verbiage, but more loudly. "I'm from Misery Boulevard / Right across the street from I Hope You Die Place," he says, perhaps forgetting to add that the Tired Rapper Highway is right around the corner.

There's less of Fat Joe this time around (he's shed 80 pounds), and it shows.

On "All," Fat Joe pushes his desire to retire -- and sounds like he has.