THE DEBATE about the interchange bench and/or substitutes will heat up every now and again.

When North Melbourne finished the game with only 17 players on the field last Saturday, the supporters of extra interchange players or substitutes had reason to push their case.

If we wanted to eliminate the random rub of the green out of the game then the evidence would be overwhelming. There is no doubt that a limited interchange bench will severely dent the winning chances of any team – Geelong and St Kilda included.

But so does inaccurate conversion, fumbles, skill errors, turnovers, the bounce of the ball, missed tackles, injuries to key players and dicey umpiring decisions.

One of the great attractions of footy is its great unpredictability. As control freaks, coaches hate it, but as a footy fan I love it.

When North led St Kilda by five goals early in the game, many of the previously mentioned uncertainties were going the Kangaroos' way. The Saints were off and North were on and all the luck of the game was going to the underdogs.

Then fortune swapped teams as the game progressed. As much as we may think it unfair, injuries have always had a major effect on the result of many games.

Interchange numbers are like the question 'how long is a piece of string?' Some think four is too many, some think four is not enough. There is no definitive answer.

I am not a supporter of the substitute idea or extra interchange players. Losing players through injury is one of the game’s random variables. Sometimes it will help, sometimes it will hinder – that's the luck of the game.

What I would note is that if interchange rotations were limited to under 40 per game the damage caused by losing a player or two during the game would be greatly reduced.

I'm on record that there are many other benefits that would also come from reducing the 80 or 90 interchanges that we currently have in most games.

The views in this article are those of the author and not necessarily those of the clubs or the AFL.