HAWTHORN is "very hopeful" Cyril Rioli will return to the club this season, but coach Alastair Clarkson stressed there was no pressure on him to come back any time soon.

Rioli has taken personal leave to return to Darwin to spend time with family, the second time the club has given him a period of extended leave in the last 12 months.

"I'm not sure whether it's going to be one week, one month, one year – we don't know," Clarkson said on Friday morning.

"I haven't spoken to him personally. All he needs to know is that he's got the support of the footy club and that support is mainly been around giving him the time and space he needs to deal with.

"We'll allow him to have that space. Graham Wright, our footy manager, (has) been in regular contact with him and over that time they'll make a judgment together and what the future looks like in terms of returning to the club."

The 11th-placed Hawks take on Adelaide at the MCG on Saturday night in what will be Shaun Burgoyne's 350th game.

Clarkson said there is a real possibility the 35-year-old could play on again in 2019, the 19th season of his career.

"We've had ongoing one-year deals for about five or six years with Shaun," Clarkson said.

"As long as physically and mentally he stays up to the challenge the game throws at him, then we'd love him to continue playing, and I'm sure that's Shaun's attitude too.

"I'd be hopeful we'll sit down with him and have a discussion with him over the next 4-6 weeks and discuss what 2019 might look for him."

As revealed by AFL.com.au, the Hawks were part of the AFL's secret trial of various rules, including having set positions for players at stoppages at a training session at Etihad Stadium last weekend.

Clarkson said the Hawks were keen to be part of the trial once they knew Etihad Stadium was available for them to train at.

"I applaud them for doing this sort of stuff, because if they are going to make some tweaks or alterations to the way they structure the game or anything to do with the rules, they want to have as much evidence of that as they possibly can," Clarkson said.

"It was two 10-minute samples and that's why they're going to do it with other clubs – it was not a big enough sample size.

"There were parts of it that looked really effective and there were other parts of it that you thought, 'Gee, that's not going to work at all'."

The Hawks coach said more information was needed before the League made a definitive call on whether rule changes were required.

"At the end of the day the AFL, as the governing body, need to make choices on what's best for the game. Not Clarkson choices, not Hawthorn choices, not any particular clubs' choices.

"We're seeing some things in our game, like the drying up of scoring, the drying up of big goal tallies by big forwards, traditional wingmen … that are maybe diluting the product just slightly.

"If we can arrest that a little bit, and make a tweak here or there that would bring back the high marking and that sort of stuff, then I think that's a good thing for the game."