It's stating the obvious, but Patrick Dangerfield leaves a gaping hole in a midfield that now has plenty to prove. Champion Data's AFL Prospectus ranks the Crows' engine room as only the 12th best in the competition and getting enough quality supply through to their array of attacking weapons looms as a challenge. Rory Sloane is a star, but will cop more heat from opponents, likewise Richard Douglas and Scott Thompson is nearly 33. Brad Crouch has all the makings of a future champion, however his injury issues are well documented. The Crows are hopeful a range of players – Matt Crouch, Rory Atkins, Mitch Grigg, recruits Dean Gore, Curtly Hampton and Paul Seedsman among them - can fill the Dangerfield breach, but the jury is out. – Travis King

Since the tail end of Jonathan Brown's decorated career, the Lions have searched for a successor in the power forward department. Year after year they delved into the draft and trade period searching for an answer, and they'll be hoping to have unearthed one – or two or three - this time around. In No.2 draft pick Josh Schache, No.14 pick Eric Hipwood and third-year academy player Jono Freeman, the raw talent appears to be in place. But until that talent physically matures, the tall forward area is still the Lions' weakness. Trading for former Cat Josh Walker should ease the burden on the younger, leaner bodies, as will a full season from the club's best midfield, who at their best will provide quality service. If everything goes to script, the forward 50 shouldn't be a weakness for too much longer. – Michael Whiting

There are many holes in a remodelled outfit coming off a wooden spoon. Leaking too many goals and a midfield lacking depth have been glaring deficiencies, but the major headache facing Brendon Bolton and his coaching staff is to find the right formula in attack to kick enough goals. Finding a classy small forward is a priority. In the past two years the Blues have traded Eddie Betts, Jeff Garlett and Troy Menzel, all capable of turning a game, as well as Chris Yarran, who could be handy in attack. How galling it has been for Carlton fans to watch Betts and Garlett shine with their new clubs. Maybe using Dylan Buckley up forward or promoting Andrew Gallucci off the rookie list could provide a much-needed solution. - Howard Kotton

Much of the talk about the Pies during their impressive NAB Challenge campaign has centred on their seeming abundance of forward options. But it mightn't be as black and white when it comes to finding a viable second tall option to partner spearhead Travis Cloke. There are certainly several likely options – Darcy Moore, rookies Corey Gault and American giant Mason Cox – but it might be too early in their development to have a consistent impact. Moore will get first crack, given his prodigious potential and his ability as an energetic support ruckman, but it is a huge ask for a second-year player. Gault has also looked the part this pre-season, as did the fast-developing Cox in the win at Geelong. And then there is the much-maligned Jesse White, who has been trialled at centre half-back, possibly as a back-up option for the injury-plagued Ben Reid. In any case, the Pies will bank on gaining strong scoreboard contributions from smaller, marking types like Jamie Elliott, Alex Fasolo and Jeremy Howe, along with resting champions Dane Swan and Scott Pendlebury. – Ben Collins

The Pies will be hoping Mason Cox can have a big impact in 2016. Picture: AFL Media

Holes emerged everywhere on Essendon's list the moment the Bombers lost 12 of their experienced senior players to season-long bans for doping breaches. But the area of most concern is likely to be the club's tall defensive stocks. From last year's backline, they are without Michael Hurley and Cale Hooker (suspended) and Dustin Fletcher (retired), while back-up option Tayte Pears is also banned. Much responsibility will be placed on former Cat Mitch Brown and ex-Magpie Michael Hartley to hold down the fort in the backline alongside James Gwilt. Former Kangaroos backman Nathan Grima has been brought on board as one of 10 top-up players, but this is an area of the ground where the Bombers might be exposed at stages throughout 2016. - Callum Twomey 

It's no secret that the Dockers are thin for key forwards. Matthew Pavlich is heading into his final season of AFL football and the club is still yet to find a long-term replacement. The Dockers have invested heavily in Matt Taberner and he has shown signs of improvement but he remains a work in progress. Michael Apeness has been injury-riddled since he arrived at the club and is still a long way from establishing himself as a key forward at AFL level. Youngster Alex Pearce has played up forward but he is a more natural defender. Beyond that, ruckmen Aaron Sandilands, Jon Griffin, Zac Clarke and Jack Hannath can all play as tall forwards as can star midfielder Nat Fyfe, but it is not their primary role. – Alex Malcolm 

The season-ending injury to Jackson Thurlow has shone a light on potentially the Cats' biggest weakness, running defenders. Corey Enright is a champion but is not getting better while Josh Cowan has battled injury throughout his career. Tom Ruggles joined the list from the VFL while Jed Bews struggled for form late last season. Bews can play but is a better lock-down defender than one who turns defence into attack. The Cats could also really experiment and try to turn Jordan Murdoch into a running defender but that is unlikely. Jimmy Bartel spending more time in defence will be considered but it looks as though a back to the future option might be most palatable with midfielder Cam Guthrie forced to reprise his early years, moving back into defence for the Cats. – Peter Ryan

After losing Charlie Dixon to Port Adelaide in the off-season, the Suns are pretty light on for tall forwards. In vice captain Tom Lynch they have one of the best prospects in the competition, but after him the cupboard is fairly bare. Sam Day is entering his sixth season but hasn't established himself as a regular contributor yet, while in 'Two-metre Peter' Wright, Gold Coast has a 19-year-old high on talent, but light on for experience. That pair will battle it out for the right to play alongside Lynch, but trying to cover the loss of Dixon's 41 goals from last year will be difficult. Jarrad Grant was recruited from the Western Bulldogs, but is more of a lead-up third tall option that a primary target. The quality and talent is there, but injuries to any of the above players would leave coach Rodney Eade with a major headache to either replace or reshuffle within his forward set-up. – Michael Whiting 

The Giants recruited Dawson Simpson over summer, youngster Rory Lobb is an emerging player and Tom Downie has showed some promise, but a quality back-up ruckman for Shane Mumford remains the only area where the club looks thin. Mumford turns 30 later this year, and his aggressive style of play, coupled with last year's serious ankle operation, means his body has taken a beating. Simpson gives GWS a physical presence but he's only managed 28 games in six years and isn't mobile enough to counter the premier big men of the competition, while Lobb and Downie are athletic but lack the mature bodies needed at stoppages. The Giants ranked 14th in clearances and last in centre clearances in 2015. - Adam Curley

If Shane Mumford goes down again, the Giants will be in trouble. Picture: AFL Media

For three years, rival teams have been searching for a chink in the armour to help bring down the Hawks juggernaut. Needless to say, it's been a largely fruitless exercise. The Hawks boast the League's most potent forward line, stingiest defence and, as things stand, a midfield with speed, skill, leadership and versatility. However, the Hawks' three chief ball-winners last year were Sam Mitchell, Luke Hodge and Jordan Lewis and this season they will again form a key part of the League's second-oldest midfield. While that trio are at their peaks, the Hawks will remain formidable, but any injuries or dips in form to those champions would put pressure on the next generation to prove they're ready to pick up significant slack. – Travis King

For a player that did not play the first nine games last season, Melbourne's reliance on big man Max Gawn could not be any greater. Should Gawn go down with injury, the Demons' back-up options appear extremely thin. Jake Spencer has senior experience, having played 36 senior games for the Demons, but he does not have the presence around the ground that Gawn possesses. The next pure ruckmen on the list are youngsters Mitchell King and Max King, neither of whom have played a senior game. The other area on the ground that creates plenty of debate is the second tall forward spot alongside Jesse Hogan. Chris Dawes' durability has been a major issue and he appears unlikely to be fit for the start of the season. That leaves the developing Sam Frost and journeyman Cam Pedersen battling it out for the position. To avoid opposition teams double-teaming Hogan at every opportunity, Melbourne desperately needs to find other avenues to goal. - Ben Guthrie

With Ben Cunnington, Jack Ziebell and Andrew Swallow all among the competition's better stoppage players, North has the inside grunt to match it with most teams. However at times last season the Roos' lack of outside run and class let them down. They aggressively tried to address this need in last year's trade period, missing out on Adam Treloar, Hamish Hartlett and James Aish but netting Jed Anderson from Hawthorn. Anderson struggled for senior opportunities in his three seasons with the Hawks but has shown enough over this pre-season to suggest his speed and hardness will be a welcome addition to North's forward line. The Roos are also hoping to get a full season out of Daniel Wells for the first time since 2013. If Wells can shrug off the injuries that have dogged him recently, North's midfield run should suddenly look a lot stronger. - Nick Bowen  

With Patrick Ryder sidelined for the 2016 season, Port Adelaide has lost one of the key weapons it hoped would catapult the Power into premiership contention. There is little doubt that the pressure on Matthew Lobbe is set to amplify heading into this year. The Power ranked fourth in the competition for clearances last season, pointing to the importance of having a dominant ruckmen supplying their high-quality midfield with plenty of the ball. According to Champion Data, Lobbe's hit-out to advantage percentage is nine per cent which is classified as below average for a ruckman. The former vice-captain will need to improve this substantially if the Power are to make any headway in finals this season. Dougal Howard and Billy Frampton, both 19, are the depth options but are yet to play an AFL match emphasising the Power's reliance on Lobbe. – Ben Guthrie

Matthew Lobbe will shoulder most of Port's ruckwork this year. Picture: AFL Media
 

The Tigers knew they were light on for inside midfielders in 2015 and traded accordingly, securing ex-Giant Jacob Townsend and Andrew Moore from Port Adelaide. It is still, however, their weakest position on the ground in terms of quality. Led by captain Trent Cotchin with support from Anthony Miles, the Richmond midfield is ranked No.13 in the AFL by the Champion Data Prospectus. The more time Dustin Martin and Brett Deledio spend in the midfield the stronger it looks, but the next rung of clearance players includes outside types Shane Edwards and Brandon Ellis, whose strengths lay elsewhere. Townsend and Moore will add depth to the Tigers' midfield, but the big jump will come when promising youngster Corey Ellis is ready to contribute consistently at AFL level. – Nathan Schmook 

The Saints have an abundance of ball-winners but outside run is an issue. Jack Steven and Leigh Montagna are gun midfielders who can break lines, while Shane Savage does it from half-back. When it comes to players who have consistently been on the park, that's about it at St Kilda. Nathan Freeman was recruited for that reason, but persistent hamstring injuries have so far kept him off the park. Jack Billings and Jade Gresham are both excellent kicks and add class through the midfield. They should help St Kilda pierce through opposition teams. Eli Templeton spent much of 2015 in the VFL but if he can find the form of his debut year and shift up to a wing, he may be able to help the Saints with their run. - Dinny Navaratnam

Midfielders with genuine speed are lacking at the Swans and while Josh Kennedy, Luke Parker, Dan Hannebery and Tom Mitchell are guns, they're not known for their pace. Gary Rohan (hamstring) and Ben McGlynn (hamstring) are struggling for fitness, which only doubles the pain of losing Lewis Jetta to West Coast last year. Co-captain Kieren Jack and Harry Cunningham bring pace to the on-ball division, along with Zak Jones, but he's only played a half of footy after post-season knee surgery and is likely to play in defence in 2016. Youngster Isaac Heeney could be the answer, but he's still only 19, and knee tendonitis has limited his training over summer so that might prevent him being able to play on ball full time. - Adam Curley

Nic Naitanui's presence would suggest the ruck area is a strength for West Coast but a closer look reveals that the reliance on Naitanui means it could be an Achilles heel given his injury history. Naitanui's best seasons of 2011, 2012 and 2015 have helped the Eagles play finals but his injury-ravaged seasons of 2013 and 2014 saw the Eagles miss out on September. The Eagles aren't flush with depth in the ruck department following the loss of Callum Sinclair and they are still unsure of who is best suited to partner Naitanui. Scott Lycett signed a four-year deal at the end of 2014 but has not developed as quickly as the Eagles would have liked although his talent is obvious. Experienced ruckman Jon Giles has been recruited to provide some depth, but the Eagles only have three players over 200cm. Fraser McInnes is the fourth ruck option at 197cm, while it has also been suggested that 195cm utility Jeremy McGovern can play there if need be. – Alex Malcolm  

Last year's heart-breaking elimination final loss to Adelaide showed there's a query over the Bulldogs' key defenders after Taylor Walker's match-winning performance. The Crows' captain's opponents that night, Fletcher Roberts and Joel Hamling, both look long-term answers but they lack experience and need to put on size. The Dogs certainly went for size in the draft to help address the problem, with man-child Kieran Collins and mature-aged beast Marcus Adams impressing over the pre-season and both are every chance to play round one against Fremantle. While not the tallest key defenders going around, the duo are aggressive, competitive and are sound decision makers. With the club rapidly approaching a premiership window, at least Luke Beveridge now has a few options to confront the competition's monster forwards. – Ryan Davidson

- See more at: http://www.afl.com.au/news/2016-03-09/your-clubs-achilles-heel#sthash.49U7z5qy.dpuf