"We learned last week that we can't be putting two or three people into the breakdown, particularly when you have guys like Sonny Bill offloading when he has two guys hanging off him; Richie McCaw as well, I saw him almost give a phenomenal (pass) to Vito in between two players."
Another in the Irish camp to notice William's improvements has been backs coach Les Kiss, an Australian who played league on the wing for the Kangeroos.
"The last six months when he's been with the Chiefs and controlling that midfield he's come on in leaps and bounds," he said. "It's not an easy thing that transition from league, it's a different environment at the breakdown and at contact."
Asked if the forecast wet and windy conditions would suit Ireland more than the All Blacks, Kiss said: "I've seen the All Blacks play in these conditions.
"Last year during the World Cup against Australia conditions were a wee bit wet, would that have made a difference? I don't think so, I think we were always going to win that game.
"In the northern hemisphere we play in those conditions a bit more but I wouldn't say it gives us an advantage. Whether it's wet or dry you still have to maintain that advantage, maintain possession and not give away silly turnovers. You still have to make your tackles."