Gerrard was deployed in a holding role by Brendan Rodgers over the second half of the campaign, helping Liverpool to 11 consecutive wins and their most serious title challenge in the Premier League era.
The Reds skipper was nominated for the PFA Player of the Year award for his displays, and Barnes believes that he has always been capable of excelling in a deeper role.
"I have said this all along to people. I remember speaking to Didi Hamann about it, because Didi didn't know Steven Gerrard as a young kid who was able to do that. When he came, Steven was an all-attacking midfield player, and Didi is surprised that Steven can do this. I'm not surprised at all. I knew Steven when he was a young boy, in my last year at Liverpool," Barnes told the club's official website.
"If it had been decided, he decided or it was decided for Steven as a 16-year-old, to be a holding midfield player, he would have been the best holding midfield player in the country, the best defensive midfield player in the country. What was decided, either by him or the club, was that he would be an attacking midfield player, so he became the best attacking midfield player in the country.
"So this is not a role that is alien to Steven, this is not a role that Steven can't do to a world-class proportion. So it doesn't surprise me at all that he has done it, because it's very natural for him to do it as he gets older. He has been the best defensive midfield player in the country. People may have been shocked by that, but I'm not."
Liverpool eventually finished two points behind champions Manchester City in the final Premier League standings.