Several veteran All Blacks have had slow starts to the Super Rugby season.

Indications that several of the 2011 World Cup-winning All Blacks might not be around to defend the title in 2015 may become clearer as mid-year internationals approach and the Super Rugby season reaches its 12th round.

When All Blacks coach Steve Hansen recently accepted a contract extension to coach until the next World Cup, he raised the possibility that some senior players may not figure in his 2015 plans.

Hansen introduced nine new All Blacks in his first season in charge last year and said growth and renewal were essential for New Zealand to hold its place as the world's No 1 rugby nation.

That philosophy will face a practical test as the Super Rugby season progresses and leading players contend with age, injury and lapses of form.

Matches in round 12 will throw a spotlight on a number of players currently battling to hold All Blacks places, on the younger players vying to replace them and on the continuing absence of Richie McCaw.

There are five more rounds before the Super Rugby season breaks for June internationals, including the All Blacks' three-test series against France for which, on current form, several World Cup players - among them Israel Dagg, Ma'a Nonu, Keven Mealamu, Andrew Hore and prop Tony Woodcock - might not be selected.

That points to the fact the 2011 side, thought to be the foundation of a 2015 Cup bid, already might be in decline.

Of the 22 players who took part in the 2011 World Cup final, five have already left New Zealand or are no longer available for All Blacks selection.

From the starting 15, blindside flanker Jerome Kaino is now playing in Japan, as is his substitute, Adam Thomson.

Lock Brad Thorn moved to Ireland and then Japan after the World Cup and, though he is now playing for the Highlanders, he is 37 and retired from test rugby.

Sonny Bill Williams has returned to the NRL while substitute first-five Stephen Donald moved to England and is now nearing the end of his contract at Bath.

Cory Jane and Richard Kahui are both injured. Jane has taken no part in the current Super Rugby season because of a knee injury while Kahui suffered the most recent of a series of shoulder injuries last weekend and his playing future is bleak.

McCaw will take no part in Super Rugby this year after taking a "sabbatical" designed to allow him to fully recuperate from the hard knocks of international rugby.

The 116-test veteran, now 32, is scheduled to play his first major match of the season against Australia at Sydney on August 17.

Whether he returns from the long layoff a fresher and fitter player, or disadvantaged by a lack of regular play remains a bone of contention.

Crusaders chief executive Hamish Riach confirmed Thursday the side had been financially compensated by the NZRU for McCaw's absence and acknowleged public concern over the sabbatical system.

"In a very general sense I can see what that concern is and, yes, I agree with it," Riach told Fairfax media.

"But we do want the All Blacks to be successful. We would hate to see them go through a test series without depth and go through the disappointment of losing tests."

Carter missed several recent matches for the Crusaders while on leave of absence to be present at the birth of his first child and with a hamstring injury. His fitness and form remain an ongoing concern to the All Blacks' selectors.

Dagg has been dropped to the bench by the Crusaders for Sunday's match against the Brumbies after looking low on form and confidence this season.

Mealamu, who started at hooker in the World Cup final, will make his first starting appearance of the season on Friday for the Auckland-based Blues against the Stormers.

The 102-test veteran in an example of a senior All Black, integral to the World Cup success, who is now under pressure to find his best form.

Mealamu came off the bench in the Blue's last three matches after missing most of the first half of the season while taking an extended break from top rugby.

"It was all part of the plan. Kevvie's had his long break and we've brought him back into it," Blues coach John Kirwan said.

"We're looking for him to get back to the great form and the great player that he is."

Hore and Woodcock's form has been of concern as the Highlanders have plunged to the bottom of the table, winless after 11 rounds.

Nonu also remains well short of his best form.

There are World Cup veterans who have shown form this season, among them No 8 Kieran Read and lock Sam Whitelock who have been outstanding for the Crusaders, Conrad Smith and Piri Weepu.