MELBOURNE, AUSTRALIA - AUGUST 06: Sam Mitchell and Luke Shuey of the Eagles look dejected after losing the round 20 AFL match between the St Kilda Saints and the West Coast Eagles at Etihad Stadium on August 6, 2017 in Melbourne, Australia. (Photo by Quinn Rooney/Getty Images)

Every year, some teams exceed expectations and perform brilliantly throughout the home-and-away season, although some sides do the exact opposite.

In 2017, Richmond has been the main side that has defied expectations, with Essendon and Port Adelaide possibly getting the best out of themselves as well.

But which clubs have failed to show up this season and have disappointed the most?

West Coast

Despite currently sitting in ninth place and just percentage out of the finals race, the Eagles have been really poor this season.

At the end of last season, West Coast traded for Hawthorn champion Sam Mitchell and picked up North Melbourne great Drew Petrie in moves to top up a list that finished sixth and lost to the Western Bulldogs in an elimination final.

The Eagles came into the season as one of the oldest clubs in the league, and their average age over the course of the year so far is 26.6, which is almost a year older than the next side in Essendon.

After going 6-5 into the bye, the Eagles have gone 4-4 since round 13, and haven't won back-to-back games since rounds 7-8.

The future doesn't look great for the Eagles either, with just Kurt Mutimer and Luke Partington making their debuts this season, with no other club playing fewer debutants.

Add to that the retirements of Brownlow Medallists Matt Priddis and Sam Mitchell, and the impending exits of players like Drew Petrie and possibly Mark LeCras, and the Eagles get significantly more inexperienced in 2018.

With games against Carlton (h), GWS (a) and Adelaide (h) rounding out their season, the Eagles are no certainty to play finals, and if they manage to scrap in, nothing they've shown this season would suggest they could make an impact in September.

Gold Coast

It's been another really bad year for the Suns.

The Suns have lost seven of their past eight matches and are destined for another bottom four finish, which will be their third in a row.

Star player Gary Ablett is almost certain to leave at the end of the season, Rodney Eade was sacked as coach earlier in the week, and the future of co-captain Tom Lynch will be speculated throughout next season as his contract ends at the completion of 2018.

They have had some injury troubles this year, but before the season began, they would have set their sights on pushing for the eight.

With a new coach and Ablett not around, next season could be another rebuilding year for the Suns, and that's not what they need right now.

St Kilda

Given they missed out on the eight last season by just 10%, many predicted St Kilda had the potential to not only make the finals in 2017, but experts said they were a chance at a top four finish.

The Saints brought in Jack Steele, Nathan Brown and Koby Stevens to add to their depth, and Jake Carlisle came into the side for his first season due to being suspended for the Essendon drugs saga.

Without losing much talent, the Saints were poised to threaten, but never really got going this season until rounds 13-16.

After smashing Richmond to move one game clear inside the eight, St Kilda have dropped games to Essendon, Sydney and Port Adelaide over the past month, which now have them 10% outside eighth position and in 11th spot, with games against Melbourne, North Melbourne and Richmond to come.

For a side that promised a lot, they certainly haven't lived up to the hype.

Verdict: While all three clubs certainly won't be happy with their 2017 outputs, West Coast were touted as a genuine premiership threat at the beginning of the season, and they certainly have not lived up to that billing.