Andrew Mehrtens on what the All Blacks lose with Damian McKenzie at No10

Current All Blacks No10 Damian McKenzie has to begin "priding himself on the boring things", according to Andrew Mehrtens, a player who wore that jersey with aplomb two decades ago.

The 29-year-old has become the All Blacks' first-choice flyhalf under Scott Robertson in the absence of Riche Mo'unga, a role he appears to be thriving in thus far.

Having spent the early stages of his All Blacks career playing at fullback with Mo'unga and Beauden Barrett ahead of him, McKenzie has been given licence to run the team. This is even while Barrett remains in the squad currently, playing either at fullback or from the bench.

Joining the team on RugbyPass TV's Boks Office this week, Mehrtens, who was once the All Blacks highest points-scorer, gave his verdict on whether he sees McKenzie as a No10 or a No15.

While he said that McKenzie long term is a "really good No10", he said that the team miss him breaking the game up from fullback. He likes the idea of the Chiefs star at first-receiver, but prefers when he occasionally fills the role as it makes him less predictable, comparing the impact he can have on the game to Willie le Roux's for South Africa.

From one flyhalf to another, the advice he gave McKenzie was to do the boring things well. Mehrtens said that his fellow No10 has "all the skills", but must learn to balance his natural attacking game with the less glamorous side of running the ship.

"He's got a lot to offer anywhere on the field," the 70-cap All Blacks said.

"I've always liked him as first-receiver when he's playing fullback. When he comes in he's maybe first-receiver 20 per cent of the time, very similar to Willie le Roux, breaks it up, really makes the defence think 'ok, what's going on here'.

"So he's a bit more predictable, naturally, when he's getting the ball more regularly, but he's got all the skills, all the ability and I think probably him finding a balance for himself within his natural game - which is to attack from everywhere - but also just priding himself on the boring things as well. He's got a good kicking game, he's a good passer, he's brave, so I think long term he is a really good No10.

"With Beauden Barrett as well, there's also a case to be said that his best role is coming off the bench and lifting it, working alongside DMac."