 Seip became the highest scoring defender in the Eredivisie and quickly established himself as a fans favourite due to his no nonsense approach to defending.On 8 June 2013 Seip signed for reigning A-League Champions Central Coast Mariners on a three-year deal.He made his Mariners debut as a substitute in the first round of the 2013–14 A-League, coming on with ten minutes remaining in a draw with Western Sydney Wanderers.