It really comes down to our batting, and our lack of depth.
Our bowling if all fully fit would be one of the top attacks in the world, especially in one-day cricket.
We have always struggled for test match openers. Over the past 10 years, the only one with any real success has been Richardson. Players like Papps, Cumming, Bell, Fulton, Sinclair, Jones, (not all openers) have got great FC records, but can not take that into the international arena.
Teams like Aus, Ind, Eng, SA all have a lot stronger domestic competitions than us. And therefore it's a much bigger step up, e.g. often our players score a domestic 200 one week, and then are selected for the BlackCaps and get two fails the next week.
Or middle order is not that weak. Taylor, Ryder, Vettori, and McCullum, are all good batsman, but in all of their cases lack consistency at times. Taylor is really coming along in the test match arena, and that was shown in the Pak series, where he made a few 90's.
Again our team is injured plagued. Bond and Oram are both world class players, but are hardly fully fit to showcase their talent. To a lesser extend we currently we have four first team one-day players out of the Bng series, Bond, Elliot, Mills, and Ryder. The likes of Franklin and Vettori have also had injury troubles.
In terms of out test match bowling now that Bond and O'Brien are gone, it really doesn't look like it'll be able to cause much damage to Ponting, Clarke and Hussey. Southee has been in and out of the side over the last 12 months, Tuffey is only bowling 130's, but on his day is a good bowler, Chris Martin our leading pace bowling probably only has another year left in him.
Overall we are never going to be a number one or two test side in the world, just down not having enough talent, we do have the potential to move up into about 4th/5th spot though, and over the next few years we'll see if we can push ahead of the likes of SL etc.
In one dayers I would currently rate us third in the world behind Aus and SA. We do have a much better batting line-up suited to that format of the game, and a bowling attack that as I said before may be the best one-day attack in the world.