The Seagulls are one of the favourites to go down this season, despite showing their superior quality in the Championship.
Rosenior has made three appearances so far this season and he has helped Chris Hughton's men move up to 14th in the table.
After losing their first two games they then picked up four points from their next two matches and Rosenior believes they can be happy with their start.
He told the club's official website: "I think we’re on par. If you look at what our ultimate aim is for the season, it’s to stay up.
"If we achieve our Premier League status for this time next season, I think everyone would say it’s a decent season. In order to do that, I think you need to average around a point a game, and that’s where we are at the moment.
"We’ve played some very good teams, and most of them are in top half of the table."