By Marc Snetiker
Updated June 11, 2014 at 02:30 PM EDT
Keith Bernstein

Did you know that Jersey Boys hits movie theaters June 20? No shame if you didn’t; there’s been a noticeable lack of buzz around Clint Eastwood’s film adaptation of the 2005 musical, which was a certified smash on Broadway: Jersey Boys won four Tony Awards, including Best Musical, and is currently the 13th longest-running Broadway tuner in history. (It may soon be the 12th, if the show hangs around the August Wilson Theatre until fall 2015.)

When news broke that Eastwood would helm a movie based on the show, the stage community was understandably intrigued. The cast was solid: John Lloyd Young would reprise his Tony-winning performance as the show’s original Frankie Valli, joined by fellow Jersey Boys alumni Erich Bergen and Michael Lomenda, as well as Boardwalk Empire‘s Vincent Piazza. Still, the film’s late-to-drop trailer was as concerning as it was compelling. The question remained: With so few details having emerged, how exactly would Eastwood translate a beloved stage musical into a feature film?

Luckily, Piazza fielded plenty of those concerns when he dropped by the EW office to talk Jersey Boys. Theater fans, take note — the Jersey Boys movie might be exactly what you were hoping for.

ENTERTAINMENT WEEKLY: You’re the only one of the four Boys that didn’t appear in the musical. How did that throw you?

VINCENT PIAZZA: Initially, I was terrified — and realistically questioning that I would be so deluded [as] to think that in 30 to 45 days, I could suddenly acquire this hidden talent [to] hang with a four-part harmony with these incredibly talented guys. So I was a little fearful at first, but I embraced the character I was playing, Tommy. He being the one that’s maybe most diverse in his activities or distracted from music, if he missed a step, if he was off a note, maybe there’s more forgiveness. But obviously I worked hard to get to a place in the work, and wherever that was, I just had to trust the hands that I was in. And certainly there was a lot to trust — it’s Clint Eastwood.

As a theater fan, I’m curious about some of the specific variables up in the air — like the music and narration. What was the approach to getting this right particularly for theater buffs?

It’s funny, because it happened with classic stuff like Streetcar, and many, many plays — not just musicals — that have been adapted for screen. And it was a great question mark: Would something that’s great or well-received on stage hold up as a film? We’ve seen it in God of Carnage, more recently. I really think that the Jersey Boys musical — and this is just my opinion — lends itself to being cinematic in some way, because it’s a jukebox musical, the characters break into song only for the scene transitions…

So for the most part, there’s no non-diegetic music?

I don’t think so. Maybe “Earth Angel,” which is a song but wasn’t used as story. The music already had its place in pop culture, and [in the story] it was used in an emotional way that housed these memories of their experience together. I think the movie lets the story breathe more. Rather than suddenly, the lights change and the wardrobe changes on stage and they’re on Ed Sullivan or American Bandstand, you’re transported into the authenticity of the world that it’s hard to get to on stage because of practical reasons. It’s a different medium, and it lives and breathes differently. I think we get to know the guys a bit more intimately than perhaps we do on the stage. And that’s not to take anything away from the stage. The stage has this immediacy that only theater can give you, but the movie gives you something else, and although it’s faithful to the musical, I think it’ll have its own identity.

Tell me about the narration. You’re talking and looking directly to camera. At the outset of the movie, what conversation did Clint Eastwood put forth about his vision for that?

He’s so present as a director. It’s hard to tell what may have been pre-conceived or what was born on the day. But speaking to the narration, the second day of shooting, we had what typically are short scenes, more or less inserts, like Tommy leaving jail, Nick arriving in jail, and narration to top it. So we shoot one take, as written, assuming I would do the narration in the booth in post-production. And then all of a sudden, Mr. Eastwood says, “Hey Vince, come here. Next time, on the walk, just turn and look to the camera and start talking to it.” And I went, “Excuse me?” And he goes, “Yeah, just talk to the camera.” And in my head I’m nervous, because do I remember the narration? And luckily I read the script so many times that I did know it, and I just had to talk it to myself. And it was actually a great relief because those camera movements on those sweeping shots are pretty technical, so it was a great relief to me as an actor to just deal with the camera I’m looking at. It opened me up, and I started forming this friendship with the camera, which ends up being the audience.

Narration directly to camera wasn’t the approach from the beginning?

It may have been born in the moment, and there was a lot of that wonderful spontaneity in exploring. It’s great. As soon as we get to Frankie’s house and we’re in his living room, it’s so well-designed that there were things we could play with as actors.

I read that John Lloyd Young had said you were the only one initially to ad lib and improvise, because the other three had been so accustomed to never messing with the stage script.

I think it speaks back to that cultural exchange. In truth, I have to respect the text to the syllable on Boardwalk Empire, because TV is a different animal. You can’t just go in and adlib on Boardwalk, and if you do feel a line differently, there are calls that have to be made to the writers’ room, and then they weigh in. There’s a process. On this, obviously we had an incredible screenplay, and I love the fact that Mr. Eastwood maintained it. He had a great statement about it where he said, leave it to Hollywood to try and fix something that wasn’t broken. But I think what I saw as an actor was an opportunity that, knowing something works on a stage, now it’s going to be housed in a different environment, and there’s a lot of things that playwrights may imagine on the stage, and all of a sudden now you’re in this new environment and we’re wearing wardrobe that maybe no one had imagined other than the wardrobe designer, and set design that created the living room, for instance. So there was opportunity within the relationships to explore more of what was going on. I was just trying to embrace that freedom, and Mr. Eastwood certainly was encouraging of it. So we had a ball.

In a post-Les Miz world, there’s always the question of how the music is handled. Did you sing live on set, or did you dub in a studio?

For me, obviously it was all new, so I only took that this way must be the best way to do this. Mind you, any rehearsals with the singing and the dancing were simply with a piano in a very bare room, or with mirrors trying to make sure we had the moves right. So to get up on stage, and we had a live band behind us, and we were miked inside our wardrobe, and then with the actual working authentic mics of the period, and then wired down the mic stand was a third mic. So we had three ways of recording live sound, and I have to say, as an actor, purely to have that kind of live band pulsate through me while I was working was such a gift. I couldn’t yell cut or adlib during the song. The music aspect taught me so much. It was such a wonderful self-discovery thing.

The music is all live?

It’s all live. We spent one day in the studio going through the songs for anything that they needed to adjust or fix. Leave it to Mr. Eastwood. He has such integrity. I think it’s a really cool thing that he pulled so much cast from different companies of the musical, and stayed faithful to the live musical element.

Is there a particularly spectacular sequence we should really be on the lookout for?

I’ll just say that the last number pays tribute to theater in a very interesting, special way.

“Who Loves You”?

Oh, it might not be “Who Loves You.” I’m not going to tell you the last number, but it really pays tribute to the theater experience, which I think you might appreciate.

Are you all nervous about how the theater community is going to react?

Of course, and understandably. All the nerves come within not just the wider audience, but of course the community that gave us permission to do this. It’s like I said, an interesting cultural exchange, and I can’t tell you how many times you come out of a movie that was adapted from a play — or, even better, a book. How many times was a book turned into a movie and you’re like, “The book was so much better?” So there’s that translation. But it’s funny: It’s just like the movie. You’ve got four guys, and all they can do is agree to disagree. I hope the movie and the Broadway musical can co-exist with mutual respect, because the movie is faithful to it — but it’s just a different medium.