Gilbert played schoolboys rugby in the position but has played fullback and wing in his earlier Super Rugby games.
Assistant coach Clarke Dermody said the coaching staff were confident Gilbert could handle the role.
"Obviously, it is a surprise to anyone outside of the team.
"What we see is a guy with a good skillset for the 10 [first five-eighths]. It's not my area of expertise, but he has been running the team very well this week, and we're looking forward to seeing how he goes in there," he said.
Dermody said the decision was one where Brown had gone on instinct.
"He sees things better than I do in those positions," he said.
Gilbert had the natural ability to handle the role. He is a strong kicker, a good tackler and a good distributor of the ball.
His strong punt could be an asset in improving the side's positional kicking.
There was every incentive for Gilbert to succeed in his changed role.
"If he plays well, he's a definite shout to stay in there.
"It's the same as anyone that gets an opportunity in our team. If they nail it, there's a good chance they'll be there the week after," Dermody said.
"He's bigger under the high ball as well, and the way the Force play, they come through the front door, especially in the 22 early in the game. So, we're looking to negate that as well," he said.
The move was also a signal of a shift in style the Highlanders are attempting to achieve and something that has been happening in increments over the last few weeks.
But Dermody would not elaborate on that.
The midfield has also been bolstered by the return of Josh Timu to centre where he will partner Thomas Umaga-Jensen.
"There is a big body, and then someone who's a bit more agile, and has a bit of a different skill set," he said.
The Highlanders take on the Force at 7:05pm, Friday 13th May, at Forsyth Barr Stadium.