In 2011, Primus' first full season as the full-time Port Adelaide senior coach, the side won only three games, finishing second-last, narrowly avoiding the wooden spoon with a win in the final round of the season against , at the expense of . He finished 2011 with a 3-19 win-loss record. In 2012, he coached the team to a 5–13 record after nineteen rounds, but after the team's 34-point loss to struggling expansion team in Round 19, Primus was informed that his contract would be terminated one year early at the end of the season; he opted to step down as coach immediately, on 6 August 2012, rather than coach out the remaining four matches, and he was replaced by Port Adelaide assistant coach Garry Hocking as caretaker. He left Port Adelaide with a winning percentage of just 27.7%.