MICK Malthouse said recently on radio that Collingwood had three substitution models they were experimenting with.

The first two, you would assume, would be commonplace among all clubs. One would be calling on the substitute in the event of injury.

The second involves using the substitute in a tactical manner, like bringing on a fresh pair of legs during the second half of a match. He wouldn't divulge too much about the third option, other than to say it wouldn't be revealed until after round seven.

This idea of formulating responses to the subs rule is being played out across the competition as teams come to terms with a new element to the game and find the most advantageous way to maximise its use.

Going back to what Malthouse was saying, coaches must decide whether they activate the substitution strategically for tactical reasons, or hold off in case of an injury.

Teams who decide to activate their substitute early for tactical purposes are exposed if they suffer one or more injuries.

Multiple injuries remove any tactical advantage, as was the case in the Brisbane Lions' round-one loss to Fremantle.

Provided there are no injuries, the new rule is an exciting introduction.

Without injuries, the coaching mindset shifts from managing player loads and rotations to game stage, time of activation, position and maximising the advantage of a new player.

The substitute is a coach's joker card not dissimilar to the one used in the card game 500. It's his wildcard and can be used as any suit to complete a hand.

The substitution rule brings a new dimension to the game and importantly, substituted players are having a significant impact on the outcome of a match.

Last week's match between West Coast and the Sydney Swans underlined the value of a substitute.

The Swans led by 17 points at the 12-minute mark of the third term before the Eagles kicked the next two goals, reducing the margin to five points.

It was at this point that my SEN colleagues and I began discussing the idea of activating the substitute.

It made sense. With two-and-a-half quarters played, the players were showing signs of fatigue. The game was evenly poised and waiting for something or someone to influence it.

As if on cue, John Worsfold introduced his 'super sub' Andrew Gaff at the 23-minute mark.

Like the previous two weeks, Gaff had an immediate impact, kicking the Eagles' next goal to wrestle back the lead.

It was like watching a game of chess being played on the football field.

The decision by Worsfold, in part, drew John Longmire into his next move as the need to get young Swan Sam Reid off the ground because of a minor foot injury became apparent.

The Swans checked Worsfold's move by introducing Gary Rohan at the 26-minute mark and, like Gaff, Rohan kicked an important fourth-quarter goal.

Both players had a significant impact on the match once introduced.

Gaff played all 44 minutes of available game time, finishing with 12 disposals and a goal. Rohan played 40 of a possible 41 minutes, finishing with nine possessions and a goal.

The decision to introduce the respective substitutes was well-timed and executed.

The substitutions injected new life into the game at just the right time, which is an exciting by-product of the new rule.

Both substitutes had the desired effect for both teams, even for the losers.

The Eagles have used Gaff as their substitute for the opening three rounds and for good reason.

Against North Melbourne in round one, Gaff played 78 of a possible 91 minutes, collecting 14 possessions and a win in his first game.

The following week, Gaff played the last 42 minutes of the game, gathering 11 disposals in their second win against Port Adelaide.

Gaff has played 164 of a possible 177 minutes or 92 per cent of his available game time in the first three weeks, allowing Worsfold to take advantage of his running ability and aerobic capacity on big grounds like Patersons Stadium and AAMI Stadium.

The rule has worked in Gaff's favour, too, with the youngster benefiting from being able to wait for the other players to fatigue and for the speed of the game to slow down before being unleashed.

The negative for any substitute is, if he doesn't play sufficient game time what impact will this have on his selection for the following week.

Mark Seaby, Kane Lucas, Brendan Whitecross, Neville Jetta, Alwyn Davey, Josh Toy and Dennis Armfield were all dropped the week after playing as a substitute.

Teams will continue to explore the best way to maximize and manipulate the substitution rule and provided there are no injuries it is an exciting introduction.

I have a couple of "Best Utility" trophies in my garage from my junior playing days.

These awards were normally given to the kid who didn't play in any one position and wasn't good enough to finish in the top three of the best and fairest.

In 1982, I thought coaches gave you this award so you felt part of the group and didn't feel left out.

In 2011, the substitute is not only a part of the group but arguably one of the most important components of the group.

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