Tuivasa-Sheck is still learning the fullback role - he's only played 24 games there - and has been given a lot of responsibility, for both club and country. That's a big ask for a 22-year-old but he is mature beyond his years.
"More than anything I'm excited," said Tuivasa-Sheck. "There has been a lot of talk in the pre-season, a lot of hype, but now it's like 'let's go'."
The crucial element in the equation is how the rest of the squad lift their own standards. It was nowhere near good enough for most of last year.
The jury is also out on how the Warriors will use their two new stars. The Roosters backline was a well-oiled machine, where Tuivasa-Sheck slotted in perfectly. That hasn't been the case with the Warriors back division in the past two years, often inaccurate in attack and fragile defensively. The Warriors will also have to adjust to Luke's tendency to pass moments before the defensive line, quite different to Nathan Friend's more orthodox approach.
"As soon as there's one player on the ground he's taking off and sometimes we're not used to that," admitted Ben Matulino. "We've got to adapt to his game."
"They will be big for us," said Manu Vatuvei. "Issac is a good leader, especially with all the young guys in the forward pack. Roger has got a massive role at the back, especially directing the boys around the park. They are ready to go."