The Kangaroos' decision to delist midfielder Sam Gibson left nearly everyone perplexed.

Gibson, 31, played 130 consecutive games for the Roos since since making his debut in 2012, including every match in 2017.

However, despite being named in the side's best 22 week in week out this season, plus finishing sixth in the best and fairest, it was not enough to earn a contract extension.

Gibson said earlier this week the axing was difficult to understand.

"I think Iโ€™m a pretty rational person and it can be pretty hard to fathom that you can be in the best 22 for 130 weeks and finish sixth in the best-and-fairest and not have a contract for next year," Gibson said.

โ€œThatโ€™s been tough but thatโ€™s just the nature of our industry, I guess."

North list manager Michael McMahon explained on the club's podcast on Thursday, NMFC On Air, the decision was based on the club looking to the future and rebuilding its list.

โ€œIn regards to Sam, it is probably as much as anything a reflection on where our list is at at the moment and a little bit about what our philosophy is,โ€ McMahon said. 

โ€œWeโ€™ve been pretty aggressive throughout the course of the year in targeting some of the players that we have talked about (Dustin Martin, Josh Kelly). 

โ€œOur approach to the management of our existing list has extended to that.

โ€œSome people might look at it as being reasonably aggressive in delisting a player like Sam. He has been a terrific player, he has played 130 games in a row and been a model of consistency.

"At the same time we have to be mindful about building a bit for the future.โ€

As it stands, the Roos will take picks 4, 22, 45 and 63 into this year's National Draft.