THE late Mike Royko, an American columnist, once favourably reviewed a book on the New York Mets baseball team's World Series-winning season, not because he liked the book or the Mets — he detested them — but because he found catharsis in stomping on and tearing apart the thick and sturdily bound volume. It took him hours to destroy it.

This is another, more sober age. We would not be so disrespectful towards the earnest work that went into the 60-odd pages of discussion paper and attachments released by the AFL yesterday on the laws of the game and how they might be improved.

Nonetheless, the contents affirm that only to a point can AFL football be boiled down to a set of numbers, and conclusions drawn from them. Beyond that, analysis is as instructive as tearing up a phone book. You've have to be there to understand.

The AFL predicted that changes and amendments to the rules over the past three years would make game more continuous, but slower, and would reduce collision injuries. It now concedes that the game is more continous, but is even faster. It also admits that collision injuries have not reduced at all.

Since 2004, stoppages have decreased dramatically, and this year, there is significantly more kicking to contests — a legacy of the controversial hands-in-the-back rule — and more contested possession. The aggregate is more continuous play.

"It would be predicted that the speed of the game would decrease as players become more tired, but his has not happened," the report said. "In fact, it has increased significantly." In turn, this has meant that although the injury rate has fallen — halving for ruckmen, for instance — collision injuries are as prevalent as ever.

The reason, the report concludes, is 235 per cent rise rise in use of the interchange bench from the turn of the century. The average now is 57 a game, and — if left unchecked — might rise to 80 or 100 before it becomes self-defeating.

The consequence is that midfielders especially spend less time on the ground, run fewer kilometres — but in greater bursts — remain fresher and hit each other as hard as ever. "The general trend towards greater levels of fitness, training and increasing body size of players are all associated with increasing risk of injury," the report notes.

For seven years, rugby league has limited teams to 12 interchanges a game. Adrian Anderson said he thought it might soon reduce again, to 10. The report notes that not once has a team had to play one short or field an injured player because of this restriction. It is probable that the AFL's review will favour a curb on the interchange bench.

Still, we must tread as Royko did not: warily. We are talking, after all, not about a ledger, but a sport: ever-changing, ever-evolving, ever-maddening, ever-whimsical, never easy to pin down, and for that we should be eternally grateful. Otherwise, we would all be leading the tipping.

Counter-intuitively, the AFL's documents say that on average, there are 1.4 deliberately rushed behinds per game. They also say that there are 1.4 free kicks for hands in the back in a marking contest.

Noting this, a more impetuous colleague picked up the discussion paper and flung it across the room. Fortunately, the tea lady avoided a collision injury, but only narrowly. Royko would have loved it.