The 70-year-old guitarist – who met the Boss in the mid-1960s, playing in bands together in New Jersey before becoming a member of Bruce’s iconic E Street Band in 1974 – played Silvo Dante in the hit drama alongside James Gandolfini’s mob boss Tony.
He told The Times newspaper: “I could certainly draw on my relationship with Bruce.
“Part of the obligation of being a best friend is that sometimes you have to bring the bad news, to express an opinion that they’re not going to like.
“With success like Bruce had in the Eighties, you cannot help but lose perspective. You start thinking you’re a genius, the greatest thing in the world, and who’s gonna argue with you?
“The mindset is: did you just sell 20 million albums? I was the only guy who wasn’t scared of Bruce, so I could tell him what I thought.”
There was one particular instance when he did call out Springsteen and told him to reconsider 1987 track ‘Ain’t Got You’, which sees the musician bragging about his success while insisting all he wants is love.
However, Steven explained: “We had been separate for a while at that point and he was trying to adjust from being this ridiculously successful guy, after coming from nothing.
“He was trying to be honest about his situation in that song, but sometimes you can be too honest.
“Bruce’s talent is explaining to people their lives, and giving insight and perspective to the listener.
“I had to say to him: nobody cares about your life. Nobody wants to hear about how rich you are.”
Meanwhile, the musician thinks he helps keep Bruce grounded when they’re on stage with the rest of the E Street Band.
He said: “As long as I’m on stage next to Bruce and the guys, it’s a band.
“We’ve been around a long time and the band chemistry is a miraculous thing that should not be taken for granted.
“Besides, I think Bruce likes having someone from the old neighbourhood. It keeps him grounded.”