ONE OF the first "weapons" of modern defence will be significantly blunted with the introduction of the AFL's nine rule changes next year.

The Competition Committee pored over a decade of "data and insights" to analyse game trends before sampling potential rule changes in three VFL matches in August.

New adjudications around 50m penalties are set to be among the most impactful.

Umpires will be stricter on the infringing player's attempts to delay the game, while the footballer with the Sherrin will be able to play on during the advancement.

Competition Committee member and former key Hawthorn strategist David Rath told AFL.com.au the changes were about offering a balance between offence and defence.

NEW RULES REVEALED Nine changes for 2019

"AFL clubs teach defence in layers, and the first layer they talk about is delay," Rath said.

"Delay is the first weapon of defence – if you can delay play, then you can set up.

"When someone's running with the ball during a 50m penalty; at the moment, you'll see teams trying to delay however they can, including making the player go back as slowly as possible so they can set up defensively in readiness for the player to take his kick.

"What we're trying to do is redress that, so there's no delay and the player with the ball has the initiative and the choice."

The Competition Committee prioritised three key objectives, according to Rath, the AFL's coaching innovation and education manager:

- To provide a platform for players to play on instinct

- To progress and provide the opportunity for coaches to apply unique strategies

- To ensure we deliver the best version of our game to fans

Noteworthy was that scoring was not one of them, even though the downward trend in that area was a regular piece of the commentary on the rules topic throughout the year.

"Scoring hasn't been at the forefront of what we're trying to do," Rath said.

"We've referenced the fact scoring has declined, but the measures we've put in place were not centered around the idea of, 'We want to increase scoring'.

"At the heart of it are those three core goals."

However, the rule changes and interpretations should play a role in fighting back against the increasingly sophisticated defensive systems and potentially helping the scoreboard tick over more.

One statistic the AFL's research team discovered was that the side defending a kick-in, which had just scored a behind, was about twice as likely to register the next score.

That number was important in the thinking behind new goalsquare modifications – and they don't include a longer goalsquare.

Instead, the man on the mark must be positioned 10m from the top of the square, rather than 5m, and the player with the ball can now kick or handball into play without kicking to themselves.

"You'd expect there'd be movement (in the balance between offence and defence), because we are opening up more space and opportunity," Rath said.

"The initial extended goalsquare was based on the idea of kick-ins landing further up the ground, because if there is more penetration then you obviously have to defend more space.

"But the new rule gives a much greater strategic flexibility now to the player with the ball … if you play on, you engage the defence and they've got to respond to you."

Rath is keen to see how coaches react to the implementation of starting positions at centre bounces, where six players begin in both 50m arcs, including one inside the goalsquare.

"It's going to depend what your priorities are as a coach, so, for example, a coach may want to isolate a key forward," he said.

"If you do that one v one out of the goalsquare, the opposition defence may react and want to contain some of that space, and if they control some of that space by dropping off, the rest of the forwards may be able to exploit that.

"We don't know how coaches will try and exploit that, but we're really excited about what they're going to do."

Another interesting development affects ruckmen, who will be able to grab the ball out of the ruck and benefit from the same prior opportunity rules as everywhere else.

The change was about giving the game's big men "equal footing", Rath said.

"Ruckmen have less options at the moment and know they've got to tap the ball, and sometimes they just tap the ball down in front of them, even when there is no other ruckman competing, because they've got no other option," he said.

"Our charter says we want to see different types in the game and at the moment, rucks are not able to show their full skillset.

"This gives ruckmen more instinctive capacity to play what he sees in front of him instead of this really artificial look of 'I can't grab it, because I'm going to be tackled'."

Rath also said the AFL was happy to trust umpires to make the right call on the new hands-in-the-back interpretation, which offers greater scope for players to use their strength to "protect space".

"It does (leave a grey area) and we don't shy away from that at all," he said.

"If you see what our team is trying to do with the game, we're trying to simplify it. Interpretation is one of those elements we're trying to simplify.

"There is grey in our game and we trust our umpires to make those judgments, whereas in the past we've tried to codify every single possibility of rules."