Defender Tim O'Brien says it was hard to cope with the mixed messages at Hawthorn last year, and he's got no idea which of his former teammates will follow him out the door.

O'Brien sealed a switch to the Western Bulldogs as an unrestricted free agent on Thursday on a two-year deal.

The 27-year-old's exit from Hawthorn could be the first of many over the coming days, with new coach Sam Mitchell reportedly ringing rival clubs in a bid to offload some of the Hawks' ageing guns.

Contracted stars such as Tom Mitchell, Chad Wingard, Jaeger O'Meara and Jack Gunston are reportedly some of the players who Hawthorn are open to trading at the right price, with the club desperate to snare at least one more high draft pick to help set themselves up for the future.

The Hawks have missed the finals for the past three seasons, and their poor form this year led to the confusing and protracted exit of coach Alastair Clarkson.

Clarkson was initially set to coach on for one more year before handing the reigns to Mitchell.

Despite the club insisting that it would stick to that plan, it eventually fell apart and Clarkson stepped away to allow Mitchell to take over a year earlier.

O'Brien was in the final months of his contract during that period, and the confusion of the coaching situation added further uncertainty to the defender's future.

"It was pretty tough. Everyone handled it differently," O'Brien said.

"It affected some more than others. Obviously myself without a contract, there were question marks about what it meant for me.

"With all the different messages that were coming across, it was hard to get a grasp on exactly what was happening."

As for who else could leave Hawthorn in the coming days?

"I'm from afar now, I just have to watch and see what happens. It will play out as it does," he said.

O'Brien arrived at Hawthorn with pick No.28 in the 2012 national draft, and he watched on from the sidelines as the Hawks won the next three AFL flags.

He also failed to make the side for the club's 2016 and 2018 finals campaigns, meaning O'Brien has now played 97 games without tasting finals action.

He's confident that will change now that he's at the Bulldogs, who lost to Melbourne in this year's grand final.

"It's what you play footy for, to be playing finals," he said.

"I'm yet to taste it, and that was one really exciting part of joining the Bulldogs - they're right in that window at the moment."

O'Brien can play up forward or in defence, with Bulldogs coach Luke Beveridge keen to use the 193cm swingman off halfback.

Meanwhile, Bulldogs ruckman Jordan Sweet is off the draft table after re-signing for a further two years.