UMPIRES will be alert to defenders rushing behinds when under no pressure, but the AFL doesn't intend to tighten the interpretation of the rule introduced in 2009.

The AFL has conceded a deliberate rushed behind should have been paid against Sydney Swans' defender Harry Cunningham late in the first quarter against Geelong on Saturday night, but the League believes the rule is having the effect intended when it was introduced.

The deliberate rushed behind rule was changed after Hawthorn conceded 11 of them in the 2008 Grand Final and former Richmond defender Joel Bowden deliberately rushed behinds late in a game against Essendon that season to protect a six-point lead.

The change meant a player who rushed a behind when under no pressure conceded a free kick at the top of the goal square, with umpires instructed to give the benefit of any doubt to the defender under pressure.

It was applied correctly just once last season when Richmond's Dustin Martin conceded a free kick for handballing through a behind when under no pressure, and then incorrectly when Rohan Bail was pinged for a deliberate rushed behind when under pressure from a number of Western Bulldogs.

There have been no similar circumstances comparable to Martin's error this season, but the AFL believes that despite it being rarely paid, the rule remains a deterrent for the blatant rushing of a behind.

The number of rushed behinds as a percentage of scores has slowly crept up since the rule was introduced in 2009, sitting at 2.9 per cent so far in 2015.

The year the rule was introduced, the number of rushed behinds as a percentage of scores dropped from 3.1 per cent to 2.1 per cent, but since then steadily crept back up.

In real terms, however, the average number of rushed behinds per game is now just 4.8 compared to 6.0 in 2009, as scoring has dropped in recent seasons.

AFL football operations manager Mark Evans told 3AW that only two deliberate rushed behind free kicks were paid in 2014, and he could not recall any being paid so far this season. 

He said the AFL was becoming alert to players' attempts to hide their intent.

"I think it's something we need to look at," Evans said.

"It might have been we thought a player was under pressure, but I also think players have become a little bit more clever at disguising it."

Fremantle defender Nick Suban handballed the ball through for a rushed behind on Sunday against St Kilda, after receiving a handball from teammate Michael Barlow with pressure being applied from a Saints opponent running at him.

The umpire gave the all clear and a rushed behind was awarded to St Kilda with the umpires given a tick for that decision by the League, although it looked borderline. 

North Melbourne has conceded the most rushed behinds per game this season (56), with Richmond (55), Essendon (52) and Hawthorn and Greater Western Sydney (51 each) being the only other clubs conceding over 50 rushed behinds. 

Average rushed behinds in recent seasons

                  Per Game                  % Of Score

2008               6.0                               3.1%
2009               3.8                               2.1%
2010               4.6                               2.5%
2011               4.4                               2.4%
2012               4.6                               2.5%
2013               4.8                               2.6%
2014               5.0                               2.8%
2015               4.8                               2.9%

Stats supplied by Champion Data