A 350 per cent increase in the number of players banished from the field for 10 minutes this season has all but put paid to the re-introduction of a five-minute sin bin - and may even lead to more send-offs.

The return of a five-minute sin bin is expected to be on the agenda at the next meeting of the NRL competition committee on May 11, but is again unlikely to gain support.

Matthew Johns and Johnathan Thurston were among those calling for a five-minute sin bin at the start of this season but analysis of the matches in which teams have been left a man short for 10 minutes suggest it is not having the dramatic effect many, including referees, had feared.

So far there have been 28 players ordered to spend 10-minute stints in the sin bin during the opening eight rounds of the Telstra Premiership.

In comparison, there were only eight players sin binned in the first eight weeks of last year's competition.

Yet more significant than the dramatic increase in the use of the sin bin by referees this season is the fact that in 17 of the 28 cases teams forced to play for 10 minutes with just 12 players have won.

In the past, some referees had privately conceded that they were reluctant to send a player to the sin bin because they felt that leaving a team a player short for 10 minutes would have a dramatic impact on the outcome of the match.

They are even less inclined to send a player off, with former Canberra Raiders prop David Shillington the last player dismissed in 2015.

Until this season statistics appeared to support that view, with six of the teams who had a player sent to the sin bin in the opening eight rounds of last season's competition losing and just two winning.

The increase in the number of sin bins has coincided with the crackdown on teams conceding penalties within 20 metres of their try line this season, but rather than capitulate during the 10-minute period they were down to 12 players many sides have learned to survive.

On four occasions, the team with a player in the sin bin has even been able to outscore their opponents during the 10 minutes they were a man short:

Round 2: Dragons v Sharks (Jason Nightingale)

Round 3: Dragons v Titans (Jack de Belin)

Round 6: Bulldogs v Cowboys (Asipeli Fine)

Round 6: Panthers v Titans (Kaide Ellis)

With teams now managing to cope while they are a player short, there are fears that the game could become like ice hockey, which has two-minute, five-minute and 10-minute sin bins.

After scrapping the five-minute sin bin more than a decade ago, it is anticipated that teams would be more likely to commit a professional foul or concede repeated penalties near their own try line if it was to be re-introduced.

The five-minute sin bin was discussed by the NRL competition committee in November and NRL CEO Todd Greenberg said it was likely to again be considered at next week's meeting.

"We have sent more people to the sin bin than we did last year," Greenberg told NRL.com. "We will continue to do that. Every coach knows it and every player knows it. I think it is a fundamental shift for us to continue to hold the line because at the end of the day we are going to get a much better product.

"The five-minute sin bin was discussed by the competition committee last year and it was discussed at length. It was resolved that 10 minutes was still a really strong deterrent and they wanted a strong deterrent to change behaviour and they were not supportive of the five minutes sin bin because of the concern of what constitutes five in the bin as opposed to 10 in the bin.

"I have no doubt it will on the agenda in May when the competition committee meets again but the last conversation was to continue with 10 minutes."