HAWTHORN coach Alastair Clarkson has hit out strongly at the AFL's trial interchange cap, suggesting it could change the game too dramatically.

The Hawks' one-point loss to the Western Bulldogs at Etihad Stadium on Friday night was the first game in which the cap of 80 interchange rotations had been in place.

It will remain that way for rounds two and three of the NAB Cup, before the AFL evaluates its effectiveness and decides whether to introduce a cap for the 2014 home and away season.

Clarkson called on the League to move with caution.

"It's a pretty dramatic change to go to 80," he said.

"No-one really knows what's going to happen to the game.

"Hopefully common sense will prevail and if they want to introduce a cap, then they cap it at something sensible like 120.

"Then we can see what a minor cap on interchange does to the game, rather than take it to 80.

"There's not a person in the land who knows what's going to happen to the game when that happens, and I reckon it's an enormous risk to take with what's a pretty good game we've got at the moment, just on a hunch.

"We're going to say, let's put the cap at 80 and see what happens to the game.

"Well, I hope it's good, but what happens if it's no good?"

There were, on average, 131 interchange rotations per game during the 2012 season.

The trial figure of 80 chosen by the AFL is based on the 2008 average.

Clarkson also said the interchange cap made coaching more complicated, and placed greater strain on players, who were already at maximum capacity.

"It's always difficult when you've got a cap, because you're wanting to coach the players in terms of what's happening on the ground, not be worrying about counting numbers," he said.

"I could get a school kid to do that, but the coaches are having to do it.

"It's an enormous constraint.

"[For the players,] it's a bloody tough game.

"There are no set plays or stops in the game like gridiron.

"It's not a coach-driven game, it's a player-driven game, and we're just making it more and more difficult for the players in what is already a very, very complex game.

"The game is not what it used to be and will never be what it used to be, and we've got to move with the times."