SAINTS midfielder Jack Newnes and Suns tall Sam Day shape as key targets for opposition clubs if a strong free agency trend continues in 2019.

In the seven years since free agency was introduced, teams finishing in the bottom four one year have lost a free agent at the end of the next in all bar one season.

Most recently, Gold Coast finished 17th in 2017 and then lost Tom Lynch this year, having failed to allay the spearhead's concerns about the club's on-field future in a 2018 season that was just as bleak as its predecessor.

Ten of the 38 free agents who have changed clubs since 2012 have done so in similar circumstances. They include Shaun Higgins, James Frawley, Tom Rockliff, Matthew Leuenberger and Danyle Pearce.

Of 2018's bottom-four teams – Brisbane, St Kilda, Gold Coast and Carlton – the Saints and Suns appear the most vulnerable to opposition free agency raids, given Newnes and Day stand out as the most enticing 2019 free agency prospects among those clubs.

Blues spearhead Levi Casboult could also attract interest although not at the same level as Newnes or Day.

Gold Coast's prospective free agents also included forward Alex Sexton, who is coming off an excellent 28-goal season, and key defender Rory Thompson, although both are Queenslanders which could make it more difficult for clubs to lure them from Metricon Stadium.

Newnes established himself as one of the Saints' most exciting midfield prospects in 2016, finishing fifth in the club's best and fairest award and following it up with an eighth-place finish in 2017.

The wingman played all 22 games this year but failed to hit the same heights.

St Kilda's own on-field woes in 2018 didn't help him – its pre-season finals hopes crumbled into a dismal four-win season that saw it finish above just the Suns and Blues – and some opposition clubs could believe a change of environment is all Newnes needs to get back to his best.

If he can do that, his elite endurance, strong work ethic and durability – he is on an unbroken run of 110 consecutive games – will make him a sought-after commodity.

Day's body will be the primary concern opposition clubs have about him.

A horror hip dislocation sidelined 2010's No.3 draft pick for the entire 2017 season, while he missed the second half of this year after undergoing shoulder surgery.

However, Day showed promising signs earlier in 2018, playing 12 of Gold Coast's first 13 games, and is close to returning to full training.

As someone who can play at either end of the ground, the 197cm South Australian will be on rival clubs' radar now. If he stays fit and builds form next year, he will quickly move up their wish lists.

History suggests the Saints' and Suns' best hopes of keeping their men is to climb the ladder in 2019.

In six of the 10 cases where players left bottom-four teams as free agents the following year, their teams finished in the bottom-four again the following season.

In another three cases, their team finished 14th the next year.

The only player to leave after his team improved markedly the following year was Chris Knights.

The Victorian forward left the Crows after they climbed from 14th in 2011's 17-team competition to 3rd in 2012, joining Richmond in free agency's inaugural year.