The NRL will consider a transfer window after the most dramatic off-season of defections in the game's history.

CEO Todd Greenberg revealed on Friday he was open to the idea of a trade period similar to the AFL amid concerns about the state of the chaotic player market.

As it stands, players can sign for a rival club over a year in advance because of the way the NRL season is structured.

South Sydney star back-rower Angus Crichton penned a deal with arch-rivals the Sydney Roosters for the 2019 season before setting foot on a field in 2018.

Players can sign on the first day of the season, which starts on November 1, meaning they can put pen to paper 16 months out from when they might pull on a jersey for that team.

Greenberg said during collective bargaining agreements negotiations with the Rugby League Players Association they had agreed to consider a transfer window.

"There has been a lot of player movement and that has created a lot of good content for (the media) and lots of debate for fans," Greenberg said.

"But we also understand the flipside of that where fans get disillusioned when players are leaving.

"If you look back in the history, the game has changed a number of times without finding the perfect solution."

Greenberg said he feared any tightening of restrictions on player movements would lead to negotiations being carried out against the rules in secret.

In 2006, the NRL dumped anti-tampering laws - which outlawed players negotiating with rivals clubs until the final six months of the season - because the rules were being flouted.

It was a well-known secret that managers carried out negotiations with clubs in secret prior to the June 30 deadline and on July 1 numerous clubs announced big-name signings.

Asked if it was bad look for the game that a player such as Crichton would play the 2018 season knowing he will be elsewhere in 2019, Greenberg said: "I understand that criticism and I'm open to finding a better solution if there is one.

"In saying that, we've got to be careful we don't make rules that then get passed into cafes and corridors of private conversations.

"At the moment it's pretty transparent about the dates, players are pretty transparent and I'm conscious that I don't want to push things underground where it just becomes innuendo, which is what the game went through."