The AFL Players Association's push for free agency has met with a guarded response from AFL coaches.

The AFLPA has presented the league with a 70-page submission outlining its plan to overhaul the existing trade system which it believes amounts to a restraint of trade.

Under the association's plan, clubs would be required to match an offer from a rival club to retain an out-of-contract player with four years service, while players with around seven years service would be entitled to move to the club of their choice.

"I know the AFLPA is concerned about the decline in the number of trades that have happened in the last few years," said Western Bulldogs coach Rodney Eade.

"I think we've got to be careful that it's not too easy for players just to change on a whim."

"If any club's put four or five years into a player developing and all of a sudden he wants to go and it’s very easy to go I just think that destroys the nature of the draft where you've put some time and effort into a player."

"I'm certainly not against it but I would certainly like to look at it (so) that it's not too easy for players to change clubs either."

St Kilda coach Ross Lyon described the existing trade system as 'reasonable without being perfect'.

"I know (free agency) is a concept that exists overseas," Lyon said.

"There are good reasons for it to exist, but clearly the rules of the competition, the salary cap and the draft has really encouraged some clubs to be able to lift off the bottom."

"I think we’ve got to be careful with anything that tampers with that."

"I'd be shooting from the hip. If I sat down and had all the facts and could work my way through it, I'd be able to make some observations and have an opinion on it."

"But at this stage it's really a headline for me and something as a club we'll look at probably having an opinion on and be asked to be put forward to the AFL."

Essendon coach Kevin Sheedy believes there would need to be a 12-month lead-in period if free agency was introduced.

"It would be very difficult for the clubs and the players to say it's happening this trade period. That would be very, very awkward for everybody," he said.

"I think the players and the Players Association are probably sick of getting hit over the head time and time again in certain areas and they'll probably say let's run a freedom card."

Sheedy said his preference would be to introduce a mid-season draft.