Henry Rounce: Why Sonny Bill Williams must be in the All Blacks' Rugby World Cup squad

OPINION: Fans and experts alike have been quick to show Sonny Bill Williams the cold shoulder after his latest injury setback.

The star All Blacks midfielder succumbed to another problem on the weekend, forced to reluctantly leave the hallowed Twickenham turf in the first half with a Grade One AC joint.

In layman's terms, a shoulder injury, but it's fitting the injury occurred on the AC joint, because the heat has been turned up on his future in the black jersey.

So let's pour a whole heap of ice on that theory.

Sonny Bill Williams must make the All Blacks squad for next year's Rugby World Cup in Tokyo.

There's no doubt the 33-year old has battled a list of injuries in 2018 that are almost as congested as the team's midfield options. Chuck wrist, shoulder and knee problems into a blender and you've got a season to forget.

Perhaps as a result, Williams has struggled to hit top gear this season, but his skillset is a must for Japan.

Crucially, Williams offers something that no-one else in the All Blacks squad - or even New Zealand rugby - does. His ability to offload draws in swarms of defenders, creating space for the likes of Rieko Ioane to prosper.

Williams has put his own spin on the offload, which is not so much a conventional pass in the tackle as a giant crane arm that swings up and down, side to side, waiting to latch onto a willing runner.

That type of unpredictability is such an asset against a structured, defensive team. Look at how successful Damian McKenzie was with his mazy jinking and jiving from the back against England, ducking under tackles and skipping across the ground.

On rugby's biggest stage, the All Blacks need all the options they can get. Dual playmakers, wingers that are good under the high ball, athletic loosies, conventional ball gatherers - and Williams.

His wretched run of injuries is unfortunate, but not a sign that he's a broken man. Ryan Crotty, who replaced him against England, has also spent plenty of time watching on from the stands.

Williams has been involved in two World Cup wins - vital, big-game experience that makes him an important asset on and off the field.

His forays into boxing will always annoy people, but if the All Blacks are to land the knockout blow in Japan, they need SBW on board.

Coach Steve Hansen hopes Williams will be available for the final game of the tour against Italy, but it's a match he shouldn't play. There's no need to rush him back for an end-of-year run in the park.

A break over summer - well, as much of a break as a professional rugby player gets these days - gives him the chance to refresh and iron out any final niggles.

He'll be a big part of the Blues' plans for the Super Rugby season, even with the addition of Ma'a Nonu. In fact, the return of the veteran midfielder could work out in the All Blacks' favour.

If Nonu returns in any sort of form, Williams could find himself on the bench - not necessarily a bad thing, as he readies for another crack at the Webb Ellis Trophy.

Imagine a Williams moment of magic that wins a crunch knockout game at the World Cup. He's a genuine game-changer.

Wrap him in cotton wool, let him box, do what you like, but the All Blacks simply can't afford to offload Williams.

Henry Rounce is a reporter for Newshub Sport