Unbeaten in 13 tests in 2012 and having produced outstanding rugby at times, the All Blacks under coach Steve Hansen are doing plenty right.

They talk of having more to come, of the development of this side still being in its infancy. It's not obvious where they could find major improvements but there is one facet of their work, or more accurately the coaches' work, they haven't consistently got right - and that is judicious and effective use of the bench.

As selectors, Hansen, his assistant Ian Foster and Grant Fox have been faultless - they haven't picked a team to date that has left room for debate. Largely the personnel on the bench has made sense, too, but only occasionally this year have reserves been injected and made significant impact. Piri Weepu was a game-changer when he came on in the wet and wind of Wellington against Argentina. Cory Jane transformed the Italian test - a game which may have been changing anyway before his arrival and the decision to bring Aaron Cruden on in Brisbane and shift Daniel Carter to second-five for the final 20 minutes worked well.

But the more lasting impression of 2012 has been of the All Blacks having control after 60 minutes, emptying the bench and losing momentum. That was the case when they beat Ireland in both the first and third tests and to a lesser extent when then they beat Australia 22-0 at Eden Park.


And it was the case when they beat Wales in Cardiff last week - something Hansen took responsibility for after the game. The mass entrance of bench players is frustrating and rarely works in the sense it enhances the momentum, but when the All Blacks have the game in the bag with time remaining, Hansen sees that as a chance to provide game-time.

"It has been a long year and once we got to 33 points ahead we were comfortable we were going to win the game," said Hansen. "We wanted to go to our bench, too - that is no disrespect to Wales - we have got to be smart about what we were doing as we had another game next week and more games next year.

"Giving people an opportunity to get out on the park is massive. There is a lot of noise, you don't hear the calls and you have to learn how to adapt and adjust to that so maybe by putting everyone on we lost a little bit of shape."

Learning when and who to take off and who to put on is tough: it is not an exact science and Hansen alluded to the inherent difficulties of this task when explaining why Brodie Retallick is starting ahead of Luke Romano at Twickenham. He made reference to Retallick's bigger engine and gut feel that after a big rookie season, Romano would benefit from starting on the bench against England.

But given his time again, he would have taken Sam Whitelock off and not Romano against Wales. "I probably should have subbed Sam off because he ran out of petrol. In hindsight we took off the wrong bloke."

The bench is a weapon and it is one the All Blacks this year will feel they have used well strategically in the longer-term, but need to get a better handle on game-to-game next year.