The squad is the strength of a team; the ability to change personnel with minimal effect on performance, and results, is the mark of a champion team. It was certainly the mark of New Zealand's 2011 Rugby World Cup champion All Blacks as Graham Henry called Stephen Donald up from a fishing holiday to play the title game after Dan Carter, Aaron Cruden and Colin Slade had fallen by the wayside, injured.

ESPN's Rugby World Cup depth chart was established to gauge the absolute depth of the respective title candidates, to show which, if any, teams had the deepest squads. Rather than selecting a World XV, we're listing four players in each position, irrespective of nationality, according to form in the past six months. (We have listed eight wingers and eight locks rather than specifying left and right.)

There has been controversy, of course, with the decision in round 2 to drop All Blacks legends Dan Carter and Richie McCaw because players were more "in form" - not least because fellow New Zealanders were included. The fact they have been unable to play their way back into the depth chart is not a slight on the legends (it is a sign they are simply not playing as well as others). The form of McCaw and Carter remains a point of conjecture in New Zealand even as high-profile pundits such as ESPN's Craig Dowd "doesn't share the concern that many are feeling about the form of some leading All Blacks", saying there's a lot of rugby still to be played, but their performances now are not the major talking point - especially as the All Blacks have Colin Slade and Sam Cane playing so well that they are included in the depth chart. The major talking point in New Zealand now is injury.

The All Blacks' depth is being stretched with an increasing number of players on the sidelines, or having been on the sidelines this season. McCaw, Brodie Retallick, Conrad Smith, Jerome Kaino, Charles Piutau, Patrick Tuipolotu, Aaron Cruden, Beauden Barrett and Sonny Bill Williams are all frontline players for the Rugby World Cup champions and favourites who have spent more time than is desirable on the sidelines; Cruden, ostensibly the No.1 fly-half, has already been ruled out of the Cup, and Tuipolotu, a second-row of seeming increased importance, is in doubt with a groin issue that stubbornly refuses to heal. The form and fitness of these stars right now is irrelevant if they are fit and firing come September. For the time being, however, it's a discussion point worth debating, and it's influenced a few key positions in the fourth edition of ESPN Rugby World Cup Depth Chart. That said, the Kiwis still look strong.

Scotland's Stuart Hogg - belatedly - comes in; better late than never © Getty Images

Enlarge

Full-backs

Israel Folau (Aus), Leigh Halfpenny (Wal), Stuart Hogg (Sco), Ben Smith (NZL)

Two changes here with the form and fitness of Israel Dagg and Willie le Roux on a downward curve, the pair worthy of a spot. We've included Stuart Hogg, whose omission last time round was a discussion point on Reddit, and we've moved Ben Smith from wing to his "favourite position". We had included Smith previously as a winger to reflect the position in which he was likely to be picked for the All Blacks, but surely his irrepressible form for the Highlanders will now see him New Zealand's custodian - especially with Dagg struggling. Perhaps we ought to have included Hogg last time for his Six Nations efforts, but we didn't; his continuing form for Glasgow Warriors in the Guinness PRO12 has deserved selection (especially when added to the body of his Six Nations work). We continued to consider Nehe Milner-Skudder, as are New Zealand selectors, in recognition of his scintillating form in his debut campaign with the Hurricanes, while the Scarlets' Liam Williams has also made a push. Mike Brown still has not shaken the effects of his Six Nations concussion, and that is surely a point of concern for England and their fans. And should Stuart Lancaster have selected Nick Abendanon (and other overseas-based England players) in his World Cup training squad? Good question although the point most probably is moot.

Drew Mitchell's form this year deserves inclusion, and now he's eligible © Getty Images

Enlarge

Wingers

Tommy Bowe (Ire), Juan Imhoff (Argentina), Cory Jane (NZL), Drew Mitchell (Aus), Nemani Nadolo (Fij), Napolioni Nalaga (Fij), Julian Savea (NZL), Liam Williams (Wal)

Almost all change here, with four newcomers included on the back of strong efforts in European club competition, with Welshman George North and South Africans Cornal Hendricks and Bryan Habana dropped, and Ben Smith moved to full-back. North is yet to recapture his best after his Six Nations Fullback-cum-winger Liam Williams "was brilliant for Wales and turned his potential into raw ability" during the Six Nations, and subsequent form for Ospreys could not be ignored with other underperforming. Napolioni Nalaga has been a wrecking ball for Clermont, and we're keen to see him alongside Nemani Nadolo and Niki Goneva in a dynamite Fiji backline, while Juan Imhoff has been strong for Racing Metro. Drew Mitchell is perhaps the major inclusion, rewarded for strong form throughout the campaign for European champions Toulon as he is now re-eligible for Test selection after the ARU changed the criteria top allow overseas-based players.

Outside Centres

Malakai Fekitoa (NZL), Jonathan Joseph (Eng), Tevita Kuridrani (Aus), Conrad Smith (NZL)

Tevita Kuridrani retains his spot after recovering from a shoulder injury, while Adam Ashley-Cooper is still on the way back after missing eight weeks of Super Rugby with a knee injury. But this position, fitness allowing, looks reasonably set.

Damian de Allende has been damaging with ball in hand in Super Rugby © Getty Images

Enlarge

Inside Centres

Damian de Allende (RSA), Robbie Henshaw (Ire), Ma'a Nonu (NZL), Matt Toomua (Aus)

Ma'a Nonu continues to perform brilliantly for the Hurricanes, and he is surely a lock for the All Blacks' No.12 jumper (if ever he wasn't). Matt Toomua showed in a 27-minute cameo between calf injuries that he is perhaps the most influential back in Australia, but Sonny Bill Williams loses his spot. Williams threatened to rip apart Super Rugby in his early outings, but he hasn't maintained that form and injuries have further curtailed his influence. Who to introduce for SBW? Jamie Roberts is the obvious inclusion, especially after he lost out last time on a 50-50 call despite Tom Hamilton saying "I'd also include Jamie Roberts at inside centre". But we've gone for Damian de Allende, who's been a standout performer for the Stormers in Super Rugby in which he has beaten more defenders than any other player to show the power and elusiveness of his running game.

George Ford has made a strong case for inclusion, but still he's on the outside looking in © Getty Images

Enlarge

Fly-halves

Dan Biggar (Wal), Beauden Barrett (NZL), Jonny Sexton (Ire), Colin Slade (NZL)

Colin Slade has been sensational for the Crusaders in Super Rugby, and he is the obvious replacement for injured All Blacks team-mate Aaron Cruden. Beauden Barrett is injured right now, but he had been superb for the Super Rugby leading Hurricanes and he is due to return within weeks. Handre Pollard and/or George Ford? They have their fans, for sure, and their respective sides are much better for their selection; they'd be worthwhile selections, but we have space only for four and we're content with the quartet.

Scrum-halves

Conor Murray (Ire), TJ Perenara (NZL), Aaron Smith (NZL), Rhys Webb (Wal)

No reason for change here, with the incumbents superb.

No. 8s

Jamie Heaslip (Ire), Kieran Read (NZL), Duane Vermeulen (RSA) Warren Whiteley (RSA)

Kieran Read is yet to play like (only) he does, but his efforts are still worthy of selection here given his previous body of work. We've stuck firm with the incumbents, which is unfortunate for Ben McCalman, Samu Manoa, Sergio Parisse, Toby Faletau and Billy Vunipola; the world is seriously stocked with quality eightmen.

David Pocock is the form player in Super Rugby © Getty Images

Enlarge

Opensides

Sam Cane (NZL), Liam Gill (Aus), Sean O'Brien (Ire), David Pocock (Aus)

The Wallabies alone could supply the four opensides, with David Pocock, Liam Gill, Matt Hodgson, Michael Hooper and George Smith all worthy of selection; the greatest irony is that Australia's incumbent and likely the man to be selected, Hooper, is playing the least impressively of the quintet. Pocock comes in for a string of simply outstanding performances that see him leading the Growden Medal count, and Sam Warburton is highly unlucky to be make way. Tom Hamilton's words that O'Brien "had a brilliant tournament" in the Six Nations was enough to see the Irishman retained over his Welsh rival. Our de-selection of Chris Robshaw last time caused a little stir, and the England captain was unfortunate indeed; his continued absence from the depth chart, and that of New Zealand's Matt Todd (and McCaw) is testament to the quality players available. South Africans Marcell Coetzee and Francois Louw are also unlucky to miss a call-up, as is Heinrich Brussow who broke an arm while making a strong case for a Test recall.

Blindsides

Jerome Kaino (NZL), Dan Lydiate (Wal), Liam Messam (NZL), Peter O'Mahony (Ire)

We've seen no reason to change this quartet, with Lydiate and O'Mahony strong throughout the Six Nations and Kaino and Messam beast-like and damaging in Super Rugby. Kaino is out currently with a finger injury but he's missed only two weeks.

Jerome Kaino is sidelined with a finger injury © New Zealand Rugby Foundation

Enlarge

James Broadhurst is charging towards All Blacks selection © Getty Images

Enlarge

Locks

Eben Etzebeth (RSA), Jonny Gray (Sco), Alun-Wyn Jones (Wal), Courtney Lawes (Eng), Paul O'Connell (Ire), Brodie Retallick (NZL), Sam Whitelock (NZL)

Brodie Retallick, like Kieran Read, his predecessor as World Rugby World Player of the Year, is not at the top of his game, and he's been absent with injury, but he retains his place on the six-month selection window. No reason for change, although the Hurricanes' James Broadhurst has produced a string of strong efforts that have seen him enter All Blacks' considerations - particularly with Tuipolotu on the sidelines.

Tight-heads

Dan Cole (Eng), Juan Figallo (Arg), Owen Franks (NZL), Ramiro Herrera (Arg)

No need for change here.

Hookers

Dane Coles (NZL), Agustin Creevy (Arg), Hika Elliot (NZL), Guilhem Guirado (Fra)

We could no longer justify the inclusion of Adriaan Strauss no matter that the Springboks rake has been performing in the under-performing Bulls pack; such is the form of Hika Elliot that has seen the Chiefs hooker pushing for All Blacks consideration.

Loose-heads

Marcos Ayerza (Arg), Cian Healy (Ire), Joe Marler (Eng), James Slipper (Aus)

We've stuck firm for the fourth consecutive edition of the Depth Chart.

Teams represented: Argentina 5, Australia 6, England 4, France 1, Fiji 2, Ireland 9, New Zealand 19, Scotland 2, South Africa 4, Wales 6

Who should be here? Who shouldn't be here?

Who do you think will move in and out of the list before England and Fiji kick-off Rugby World Cup at Twickenham on September 18? Join the debate in the comments fields below, or on Twitter using the hashtag #RWCDepthChart. We look forward to hearing from you.

© ESPN Sports Media Ltd