Host Josh Groban along with “Rising Star” experts Brad Paisley, Kesha and Ludacris. (Frazer Harrison/Getty Images via ABC)

As we know by now, serving as a judge/coach/mentor on a reality singing competition show can go really well: Just ask Jennifer Lopez, Christina Aguilera and Blake Shelton, who have all received boosts in their careers. But it can just as easily turn into a nightmare, especially if the chemistry isn’t all there on the panel: Mariah Carey and Nicki Minaj can surely tell you some stories. Nicole Scherzinger is probably a bit scarred as well.

So, it begs the question: Why are Brad Paisley, Ludacris and Kesha — all doing very well for themselves at the moment — subjecting themselves to the somewhat risky position, reputation-wise, of starring on ABC’s upcoming “Rising Star”? Especially when we’ve already seen that the viewing public is growing tired of reality singing shows?

The trio has taken great pains to assure us that this show is different from all the others (they’re “experts,” not judges) taking jabs at “The Voice” and “American Idol” in its promos. “You know those other shows where you gotta wait for results? And the judges make all the decisions? Well, we flipped that,” Ludacris boasts in one. Translation: On “Rising Star,” viewers download an app and make real-time decisions about whether to send a singer through to the next round or not.

However, on the ramp up to the show’s heavily-promoted debut on Sunday night, there have been a few bumps in the road. Multiple places have already pointed out the awkwardness that occurred on Monday night when the panel interrupted “The Bachelorette” with a segment to test out the show’s live-voting function. And on “Jimmy Kimmel Live” on Tuesday, Ludacris admitted he missed the Monday night segment because he was filming a movie — not because, as host Josh Groban told everyone, he was stuck in a helicopter that couldn’t land because of the clouds. Okay.

But you can’t really judge a show until it begins: So we’ll be tuned in Sunday to see how it goes. In the meantime, here are some theories about why each signed up to be on the show.

Brad Paisley: The country hitmaker is always a great host on ABC’s CMA Awards shows, so he obviously has a good relationship with the network. But honestly? It seems like he wants to be a TV star. Not only has fellow Nashville star Blake Shelton found a giant new fanbase on “The Voice,” but this isn’t the first time Paisley has been on the small screen. In the past season alone, he’s appeared on “The Crazy Ones,” “Nashville” and “Two and a Half Men.” Hey, Tim McGraw made the country singer-to-actor transition.

Ludacris: Peak Luda was awhile ago, as the R&B star has been busy with his movie career; notably the giant “Fast and the Furious” franchise. His new album is reportedly scheduled to come out this year (the first in four years), so it’s not a bad move to remind people that he wants to focus on music. Plus, he’s already plugged “Fast and the Furious 7” during the “Jimmy Kimmel” appearance, so expect more of that.

Kesha: The singer is back on the charts with the inescapable “Timber,” but she also made many headlines this year for a stint in rehab. She’s never been shy about sharing her personal life — such as her MTV docu-series “My Crazy Beautiful Life” — so it’s possible she wants to take control of her image and show the national viewing audience a new side to her personality. After all, she already dropped the “$” from her name.