Adam Levine. (Rich Fury/Invision/AP)

When NBC’s “The Voice” coach Adam Levine was once quoted criticizing his own show (specifically, the fact that it’s never produced an actual music star), he claimed his words were taken out of context. But on Tuesday, he visited Howard Stern’s radio show and delivered some unusually candid, harsh words about the same topic, all directed at the record labels affiliated with the reality competition series.

It started when Stern, a fellow NBC star on “America’s Got Talent,” asked Levine why “American Idol” was able to launch winners to legitimate stardom, yet no other singing show has been able to “really capture that lightning in a bottle.”

Levine hedged at first. “I’ll be relatively cryptic about what I think the big problem is,” he said. “When the baton is passed post-‘Voice,’ there’s some problems. People take over after we do this great job of building these people up on the show. There’s some real issues there.”

Translation: The winner of “The Voice” lands a record deal with Universal Music Group, which takes things from there. Depending on their genre, winners go on to a variety of Universal labels, from Republic Records (Tessanne Chin, Sawyer Fredericks) to Nashville’s Big Machine (Danielle Bradbery, Cassadee Pope).

[Former ‘Voice’ finalist reveals how the NBC singing show really operates]

Wherever they go, Levine doesn’t think the people in charge are doing a very good job capitalizing on “The Voice” fame. Mainly, he said, there appears to be no strategic career plan for what to do with the winner once they leave the show and head to a big-time label.

“The rollout of all that is still such a mess,” Levine said. “And by the way, just to clarify, this has nothing to do with what happens on NBC or with the people. In that time, we do so much great s— for these singers, and then they go to a record label that I won’t mention. But they go to a record label that f—s it up.”

“Record labels are — our business is the worst right now,” Levine added. “No one knows what they’re doing.”

Stern wondered if the labels try to rush the winner into recording and writing with a bunch of producers that have zero connection to them.

“Most of them don’t even do that! You’d be shocked to see it. The show ends, and they’re like, ‘Okay, they don’t matter to me anymore.’ This is how they feel on the other end,” Levine said. “I don’t understand why they don’t care. That’s what drives me absolutely bonkers. And then it makes me feel defeated on my end because there’s really not much I can do.”

Levine echoed his frustration of being on the sidelines when the mentees are locked into contracts with labels, and he can’t do anything to help, even if it appears their career is going downhill fast. “We get so attached and so passionate about helping these guys. And now it’s become this thing where I feel like after I want to be part of it, too, to whatever capacity I can. And I’m glad I’m saying this on air so maybe the label will get angry and f— off, so we can get somebody else to do it,” Levine said.

“But they should get angry … they’ve got the world’s greatest promotion!” Stern said, noting they’re squandering the potential of the show’s millions of viewers every week.

Levine went on about how he would change things: For starters, it’s especially imperative to rush a debut single and album, since it’s way too easy for a new singer to lose momentum as people stop paying attention, he said. “In that moment when you’re never going to be bigger … it’s been this whole meteoric rise to the top of this thing, you’re peaking right here,” he pointed out. Levine said it also doesn’t make sense for contestants to perform their new single on the finale as they’re named the winner: They’re crying and confetti is coming down, and viewers can’t even hear a thing.

Eventually, Levine acknowledged that when it comes to post-reality show success, the record labels can’t be blamed for everything: Sometimes there are personality problems when musicians develop giant egos, and it becomes difficult to work with them. “Some people are huge pains in the a–es, too. A lot of artists think all of a sudden that they’re god’s gift,” he acknowledged.

Overall, he said, for “The Voice” winners to actually make a mark, the labels have to step it up. “We do a great job,” Levine concluded. “I just wish that someone on the other end was there to do it right.”

Read more:

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