Vatuvei could be an effective nines player, given his ability to break tackles, drag in defenders and offload. But he would probably have to be used in the forwards rather than be exposed out wide.
He recalls playing in the pack only once in his career, as a 16-year-old for "10 or 15 minutes" for an Auckland development side.
"It would be hard work in there, for sure. I'd be feeling the pain so just short bursts, I think," Vatuvei laughed.
The final 18-man squads need to be submitted to the NRL next week. McFadden says Vatuvei is "definitely in contention".
"Manu would be an ideal person to play nines," he said. "He's big, fast, powerful and skilful. I know he wants to be involved but it depends on whether he's ready to play."
Like the rest of the test players at the Warriors, Vatuvei returned to training only last week. He also carries a long history of injuries, and his knees and hamstrings have to be managed carefully over a long season. That is what McFadden needs to weigh up whether it's worth the gamble of using the club's No1 winger so early in the season.
"Having the extra two players in the nines squad [increased from 16 to 18 this year] certainly helps his cause," he said. "It means he wouldn't have to play every game. But it's pretty simple. We need to see how he shapes up over the next few weeks and whether he will be ready to go."
Shaun Johnson and Sam Tomkins are also likely to play, so the addition of Vatuvei would mean the Auckland club would have three of their top-five earners featuring in the competition.
Contractual rules state that teams must include at least one of their top-five salaried players.
Vatuvei says he's raring to go after a prolonged break. He enjoyed a family holiday in Rarotonga and admits the feel-good effects of the Four Nations campaign are still resonating.
"I'm still pumped from everything that happened," said Vatuvei, who scored two tries in the 22-18 win over Australia in the final. "It was such a great feeling and an important moment for the Kiwi boys. We want that feeling back again this year."