Duncan, who is the cousin of Steven Gerrard, explained why he had to leave Melwood.
"It was a difficult decision to be honest. I was in a difficult moment at that time," Duncan told ViolaNation.com.
"Something was missing. It wasn't over money. It wasn't over anything else other than I want to play first team football soon.
"In my mind, I thought I would go and play abroad. Serie A is just below the Premier League.
"Leaving Liverpool was a difficult decision. I was only there for a year, but I didn't see the path forward for me there."