The All Black front row tests the new engagement laws during training at North Harbour Stadium late last week.

Hookers actually hooking, halfbacks putting the ball in straight - it won't be scrummaging as we've come to know it.

Rugby's new engagement laws will take scrums back 20 years, to a time when Auckland, and the Blues, buried opposition packs and Zinzan Brooke scored pushover tries in his sleep.

Wellington's better club players got their first experience of "crouch, bind, set" against Manawatu last week.

The new laws get a further outing on Friday when the Lions host Canterbury and the All Blacks at the Hutt Recreation Ground.

First impressions at the Wellington game weren't good, with the scrums still going to ground and a host of technical flaws exposed.

Given time, the laws will create a massive advantage for the All Blacks and New Zealand Super Rugby teams, says Hurricanes and Lions scrum coach Dan Cron.

"In my opinion, for the lesser scrums there's no hiding now - no tactics, no hit-and-run. You've got to man up and fight to the death now," Cron said.

Gone will be ferocious hits that teams used to hide their scrummaging deficiencies, in Cron's opinion, and often led to collapses, penalties and free kicks.

"Pretty much any South African tighthead [prop] is going to have to sharpen up a bit," said Cron.

Front rows will now fold in and bind before the referee instructs the halfback to put the ball in. That's the cue to push and without the massive stress caused by the hit, both hookers will have the opportunity to strike for the ball.

Cron said Hurricanes and All Blacks hooker Dane Coles, for instance, had never been taught to hook, but would have to learn now.

Barely a second goes by between put-in and the halfback picking the ball up at the No 8's feet now, but Cron suggested it would be four seconds or more under the new laws as pushovers would come back into vogue.

He began scrum coaching in 2007, and while he remembers what they were like in yesteryear, Cron said his most valuable resource at the moment was father Mike.

Widely regarded as the world's foremost authority on scrummaging, Mike Cron has worked with the All Blacks since 2004. Father and son have spent hours discussing the new engagement laws.

"I was just talking to the old man and he's got a great story about where [former Canterbury and All Blacks hooker] Tane Norton hooked the ball with his head, so it's going back to the old school and the old way of scrummaging."

Friday's match at the Hutt Rec ought to be one-way traffic in Mike Cron and the All Blacks' favour.

Dan Cron's not too bothered about that, in large part because he agrees with his father that the laws will revive a lost art.

There will be downsides, as last Wednesday's game showed. Packs rely on timing and referee Richard Kelly was not consistent with his put-in call, which caused collapses.

Props also need to avoid getting in what Cron calls the "deep squat position" from where they either have to shift their feet back and de-power the scrum, or hang in there and get injured, because their spacing is wrong at the engagement.

Tighthead props in Super Rugby average 61 minutes of game time but Cron says that will decrease to between 40 and 50 minutes due to extra pushing required at scrum time. That will also change how front-rowers train and eventually the body shape that's required to play there, he said.

Cron has had Wellington's top props - John Schwalger, Jeffery Toomaga-Allen, Reggie Goodes and Eric Sione - furiously working on the new engagement, as well as working contacts beyond his dad.

"I had a meeting with Grumpy Muir [former Wellington coach Alan Muir] last week and he said this will be like the early 90s scrums where it was [Sean] Fitzpatrick, [Craig] Dowd and [Olo] Brown, so I'm maybe looking at bringing an old-timer in to show us how they used to do it."