MIXTAPE MASTER: Pharrell trumped himself with the street prequel to his official major-label debut.

There’s something tragically poetic to the idea that Pharrell Williams’s new In My Mind (Interscope) blows so hard. As half of the Neptunes production team, he can make a hit for you but not for himself — there’s not a single good song here. Even more confusing: the album comes on the heels of In My Mind: The Prequel, a brilliant early-spring mixtape that proved the producer-turned-rapper can ride a beat and has a curious narrative to share too, one that turns banal bling materialism and hip-hop self-obsession into endearing childlike fancy.

Then again, last year Pharrell tried to capitalize on Gwen Stefani’s hollabacking by getting her on the hook for “Can I Have It like That?”, an unfocused rap-meets-Bond spy theme that featured Pharrell’s first outing as the MC “Skateboard P.” “She like the way my hands use her body for hand warmers,” Skateboard raps, his flow a forced, huffy distraction. The song disappeared from radio as a proven loser. And still Pharrell uses it to lead off In My Mind.

Mistakes litanize. The come-up anthem “How Does It Feel?” does better with rolling tom-tom beats and syrupy horn tones, but you wonder whether Pharrell’s vague motivational verse could cut it even in the disciplinarian’s office. Things get better on “Raspy Shit,” which has cowbells and a funky bottom and “my money green like the helmet of a fascist,” but the slow jam “Best Friend” ground-zeroes the disc as Pharrell juggles his best friend/co-Neptune, Chad Hugo, his dead grandma, and a hook about his Star Trak label. He rips Kanye West’s nasally delivery on “Keep it Playa” and “That Girl,” forcing rhymes, mangling pronunciations, eliding anything and everything. But Pharrell forgets Kanye’s supreme wit.

“That Girl” rounds out the hip-hop half of In My Mind; the back half is all Stevie-envious, MJ-aspirant R&B, Pharrell’s fragile falsetto extending well past its usual 15-second welcome. On “Young Girl” Jay-Z turns in his softest, most dumbed-down 16 yet. To think that artists turned to Pharrell to make them sound confident, better. . . Now Kanye shouts “Come on!” at Pharrell on “Number One” as if they were at the club and Pharrell couldn’t get his nerve up to approach a woman. Tails between their legs, they’ve never sounded so unconvincing.

Many have suggested that Pharrell’s first mistake was keeping Hugo away from the boards. Others have come out on the side of “You’re a producer, stick with production” — an ersatz, dehumanizing argument that Pharrell’s dabbler-rapping unfortunately supports. There’s also the popular opinion — shared even among some eds at this newspaper — that pop music is dumbed down as a rule and smart as an exception and that In My Mind is good enough as expendable fare until the next limp plop boilerplatter arrives. Fair enough, except that Pharrell is actually a fascinating rapper when he lets himself go. Back in March, he teamed with Atlanta’s DJ Drama for The Prequel, a street mixtape intended to hip the public to Pharrell’s progress as rapper. By their semi-illicit nature, mixtapes enjoy boundless sampling privileges, uninhibited by the proper record industry’s winding copyright laws. It’s a great way to leak new material while revealing an artist’s musical interests and influences. At worst, they don’t sell and no one loses much money. No wonder hip-hop, an endlessly self-referential, tradition-respecting music, flourishes at this level.

Even less a wonder then, that Pharrell, a middle-class, band-camping rap geek, would do better in this zone, too. From GZA’s “Liquid Swords” to Ice Cube’s “It Was a Good Day,” he and Drama chose beats with stylistic and historical overtones to complement Pharrell’s self-obsessed lyrics, which catalogue his wealth in meticulous baseball-card-collector detail, and his charmingly barebones flow, a straightforward speaking tone, as if his words just happened to rhyme.

True, what constitutes “rapping” has expanded, and rappers need not rap well — or even at all — to move units. “They say I ain’t lyrical,” Jeezy baits his critics on his last DJ Drama mixtape, Can’t Ban the Snowman. It’s tricky. Realness sells better than skills. And if Jeezy were a showier rapper, he’d be taking time away from his purported actual profession of drug dealing. More-polished rappers, in Jeezy’s estimation, are merely “Denzel Washington ass niggas . . . they good actors, they act real good.” The art is in developing a cult of personality — in manipulating the mechanisms of publicity and popularity. The best rappers are the best businessmen.