Geelong chief executive Brian Cook has given his backing to the AFL's effort to revamp the fixture.

But Cook remains unsure about elements of the 17-5 model, which has been flagged as an option and would result in all 18 teams playing each other once in the first 17 rounds before being divided into groups of six for the last five rounds.

READ: Get the full lowdown on the 17-5 model and the latest comments from AFL boss Gillon McLachlan

"I like the idea in principle, I just don't know how it's going to work commercially," Cook said during an appearance to promote the Big Issue magazine last Thursday.

"The reasons are solid to [introduce the 17-5 model]. 

"If you look at the television ratings, we're finding that after round 17 there are so many games where the fans already foresee a big gap in games and the television ratings are down, I think, 10 or 12 per cent during those last five games.

"So there are good reasons for [the 17-5 model]. I'm just not sure how it's going to work."

Cook is most concerned about the implications of having to fixture the final five games at such short notice.

"I'm not so sure, practically, how that's going to work from a fan point of view, from a member point of view - from a member point of view more than anything - or a corporate point of view," he said.