CLEVER WORK: Conrad Smith’s understanding of how to connect with players makes the game easier for his team-mates.

However you measure Conrad Smith, he is an outstanding All Black.

For me there are two ways to define greatness in an All Black. One is by his X-factor and impact on a game, and the other is a player's ability to stay at the highest level for an extended period.

When you look at Conrad Smith's place in All Black history you will certainly find elements of both.

When the All Blacks run out to face Australia in Dunedin next Saturday they will still have a Smith in the 13 jersey, but it won't be the one who has provided the security and stability that Conrad has for his 75 tests.

If there's one position that the All Blacks have experimented in like no other it is the centre position. Remember the 99 and 03 World Cups?

But as a coach there's nothing better than having a player you can pick week after week without hesitation and Steve Hansen has had that luxury with Conrad Smith for some time now.

Great players make others around them better. Whomever Conrad has played with in midfield, whether it be Ma'a Nonu, Sonny Bill Williams or Tim Bateman at the Hurricanes, his understanding of how to connect with those players has made their jobs a little bit easier.

There are so many unappreciated aspects about playing in the 13 jersey, let's look at what makes Conrad great.

Centre is possibly the most difficult defensive assignment in rugby. The challenge of both speed and power coming from the opposition, and the decision-making or reading of attacks requires a special feel for the game.

In most cases in midfield you react off the players around you. You need to stay connected with your second-five and wing, and almost read their minds as well as the opposition's.

The variety of defensive techniques required tests your physical attributes. But, whether it's around the bootlaces, ball ‘n' all or chasing down the opposition, Smith executes with relentless accuracy.

His work around the breakdown should not be underestimated either - both sides of the ball. With possession in the outside channels so contestable, his ability to steal opposition ball, and protect his own, has few equals in world rugby.

If Smith has an X-factor it's his ability to be in the right place at the right time. Most centres have few opportunities to be a playmaker, but he consistently is a creator in the All Black backline.

That familiar ball-in-one-hand, long loping stride and deceptive creative ability often goes unnoticed. But not by his coaches or team-mates.

He almost always gets over the gain-line, attracts multiple defenders, delivers ball into space with ease and on rare occasions he's required to put boot to ball, his execution is faultless.

Combine this with his relentless physicality, and you need search no further for the perfect No 13.

What Smith brings to any rugby environment is also significant. He has an uncomplicated approach, understands his role, has the wider game figured out and can deliver messages effectively.

Every environment needs its deputies and I would suggest Smith has been the perfect complement to the Richie McCaw leadership.

In recent years we haven't had to experience life without this guy. But someone now is going to have to fill the role while he takes his sabbatical.

It's probably only now we will start to really appreciate how very good Smith is. For 51 tests the combination of Nonu and Smith has been the standard setter of world rugby for the simple reason they complement each other so well.

Their understanding of each other and the All Black game is near impossible to replicate, but you will find no one who would argue against Smith's right to take some time out. He's well and truly earned that.

In the modern New Zealand game we talk about great centres like Bruce Robertson, Joe Stanley and Frank Bunce, and internationally you think of players like Brian O'Driscoll, Jason Little and Philippe Sella who have graced the 13 jersey.

Smith has well and truly etched his name among these greats. The only question now is: could he be the best of all time?

The next two years may answer that. Back-to-back World Cups would go a long way towards confirming his status as the finest we've seen.

Jeff Wilson played 60 tests for the All Blacks and is now a rugby analyst for Sky TV.