Inside the new issue of Classic Rock, Petrucci discusses prog as a whole alongside his thoughts on why the genre frequently tends to be negatively judged, noting that he thinks "it can come across as self-indulgent or pretentious or just kinda nerdy".
Elaborating on Dream Theater's prog influence, he continues: "But it’s funny, when we started out there wasn’t a prog-metal scene, so we just kinda combined metal and prog – like Metallica and Yes in the same band."
"Fast-forward and now there’s this huge prog-metal family tree with tons of splinters. It’s not considered nerdy or uncool now. So it kinda flipped around."
Speaking of the highs and lows of the prog-metallers' career, he continues, "The grunge period, for us, was actually great. That was exactly when [1992 album] Images And Words was released, and somehow we had a radio hit with Pull Me Under that bucked the whole system.
"But in a career the length that we’ve had, there have been many difficult moments. Obviously we’ve been through band member changes. I remember after our first record, we didn’t have a singer, we weren’t signed, nothing was working out. Then the war was happening in Iraq, and we didn’t know if we were gonna be drafted."
Elsewhere, Petrucci opens about his 'bearding' hobby and who he thinks has the greatest facial hair in rock and metal. "Well, as you can tell, I have a giant beard. I’ve always had some form of beard, from the early 90s," he explains.
"But one day I was like: let me experiment with growing a full beard. When I did that, it opened up this whole world that I didn’t know existed, this whole culture of bearded men. It’s so deep and I got really into it, to the point where I’ve partnered with a UK company, Captain Fawcett, and we’ve released a beard oil, beard balm and moustache wax."
"I think Billy Gibbons has us all beat. He’s been rocking that for ever – and that is one serious beard."
You can read the full interview in the latest issue of Classic Rock, out now. It features an all-new interview with Deep Purple, plus an exclusive official Deep Purple CD, as well as features on Rush, Status Quo, Jerry Cantrell, Van Halen, Dooms Children, Florence Black, The Darkness, Primal Scream and more.