I don't think that has a lot to do with holding stuff back, more the inconsistency of our scrummaging. To launch good scrum moves you need a good platform - a promotion of the side you want to attack. At worst it must be square. Twisted the wrong way, a bad scrum will compromise you.
For example, for a scrum near the left hand touch line, you want that tighthead side up so you take their flankers out of the equation. They are on the back foot and have a lot of ground to make up.
Look at the way Australia are scrummaging. Former Argentina prop Mario Ledesma has made a big difference and they are much more dangerous as a result. One area where we always dominated them was at the scrum, but now they have become a different animal due to their excellence there.
We need to find that too. We need to start bullying teams so we can launch our backs.
It also helps our loose forwards. If you want to launch a quick scrum attack, you're going to lose you No8 a little because he's going to de-power, get down and get on to ball. In that instance you need the other seven forwards working really hard. If you get that and your scrum isn't going back then your flankers are going to get to the breakdown quicker than the opposition and the All Blacks can cause stress off the second phase.
In a nutshell, I think we've got every avenue covered, but if we can solidify that scrum and dominate, then we'll see the All Black machine go to a different level.