ROBBIE Gray has played 244 AFL games for Port Adelaide, earning recognition as a "natural footballer" for his beautifully instinctive game. He is a player the fans (both Port Adelaide and non-Port Adelaide) eagerly watch in the hope of understanding that rare blessing of seeing a play before it unfolds.

It is a gift from the footy gods.

But what happens when you take away that instinct, that pure quality that puts Gray in a rare class of sportsmen?

We saw what unfolds while the "unintended consequence" of another rule change to Australian football robbed us a classic Gray moment.

In the 24th minute of the second term of Saturday night's no-contest at the Gabba, Gray stood the mark inside the centre square on Brisbane defender Jaxon Prior. To Gray's right, another Brisbane defender, Daniel Rich, rushed by making himself available for the handball to use his momentum to drive a kick closer to the goalfront.

Gray did as he has done in all of his 14 AFL seasons before this one - he moved off the mark to counter Rich. Sometimes defence can be exciting as attacking plays.

But this year, such an instinctive move by Gray is met with a 50-metre penalty.

Prior kicked Brisbane's seventh goal of the first half and everyone sympathised with Gray on a night when the "man on the mark" rule created more concern for its unintended consequences.

There was one Brisbane player who dutifully stood on the mark as the statue the rule demands - and was left stone cold by an umpire who failed to call "play on" while his Port Adelaide rival took advantage of space.

AFL football boss Steve Hocking calls that space "valuable real estate" - space that allows for quick movement along the critical "45 degree" and into the centre corridor, hopefully cutting back stoppages from boundary throw-ins when plays repeatedly hug the line.

"We absolutely just want greater flow, that's what we want to see," Hocking said during the pre-season when many football observers were enraged by the new rule - none more so than former Port Adelaide development coach Daniel Healy. He regards the new "stand" rule as a demand to a player to stop trying to defend.

"We want to see players do random acts and certainly more instinctive play - and take the game on," added Hocking.

And now we have seen one of the game's finest players, Robbie Gray, turned into rumble because he instinctively moved off the mark rather than stand as a statue while  Daniel Rich took advantage.

It just does not seem right.

Nor does it when forwards - knowing their opponents are compelled to "freeze" on the mark until an umpire calls "play on" - now move out to a greater arc than any tried by Lance "Buddy" Franklin on set shots for goal.

Should the "stand" rule be waived when a player nominates he is having a set shot at goal?

If a rule change forces Robbie Gray to forfeit his instinctive nature to block a player from taking an easy possession - as in the potential Prior-Rich tandem at the Gabba - then there is reason to reflect on the real value of the man on the mark rule.

Yet again the AFL has tricked up its rule book to load more pressure on the umpires. And just who at AFL House pulls apart any recommendation to see just how the "unintended consequences" can make a rule change create more problems than it solves.

If only the AFL had a place to test its theories?