RUCKMEN have already emerged as key players in the Gillette AFL Player Exchange period.

They have been involved in deals that have shocked, like St Kilda's decision to trade Ben McEvoy to Hawthorn.

And they have been part of deals that have created only a few ripples in the footy pond, like the Sydney Swans' decision to trade Shane Mumford to their cross-town rival and Richmond's effort in snaring Shaun Hampson from Carlton.

Now, as the last week of player trading kicks into gear, ruckmen remain front and centre in many clubs' calculations.

Much of the focus is on Brisbane Lions youngster Billy Longer, who has expressed a desire to join St Kilda.

Although the deal is still being put together, Longer, a top-10 pick in the 2011 NAB AFL Draft, appears likely to reach the Saints.

St Kilda has also been linked to two-time premiership player Darren Jolly, who can be claimed as a delisted free agent.

Longer's defection, when it is eventually confirmed, will leave the Lions thin when it comes to ruck stocks.

Most clubs like to enter a season with four ruckmen, but the Lions will be left with just three: Matthew Leuenberger, Stefan Martin and Sam Michael.

As a result, they are likely to look towards the draft to find a fourth big man.

The top-rated ruckmen in the draft pool are Tasmanian Toby Nankervis, Eastern Ranges follower Michael Apeness, Werribee's Ben Brown and Claremont's Darcy Cameron.

Those boys are also likely to come under consideration from the Swans, who have only three ruckmen: Mike Pyke, Kurt Tippett (who is expected to spend more time in the ruck now that Lance Franklin has joined the club) and rookie Sam Naismith left on their list.

But given the Lions' experience with Longer, and the increasingly popular tactic of trading for big men rather than bringing them through the ranks, will any club spend a high draft pick on a young ruckman?

Last year, the first ruckman taken in the draft was Brodie Grundy, who was selected by Collingwood with pick 18.

Seasoned draft watchers say it is highly unlikely that a ruckman will be selected in the first round when this year's draft takes place in late November.

It seems that the trade and free agency periods and the rookie draft are where ruckmen predominate these days.