There were several factors, with family reasons playing a big part, but Leuluai also admits the constant cycle of failure at Mt Smart took its toll.
"If we were winning, I would probably still be there," said Leuluai, who gained an early release from the final year of his Warriors contract.
"It's hard. We tried everything but couldn't get it done. I feel for the boys. It's obviously been a hard season and confidence is down. But I think they can turn it round."
Leuluai's toughness, resilience and game smarts have been missed at Mt Smart this year, and the Kieran Foran experiment, which was supposed to take the team to the next level, hasn't really worked.
But Leuluai has enjoyed being back amongst a winning culture, though the season has been far from plain sailing. He started with the high of the World Club Series victory over the Cronulla Sharks, before breaking his jaw against Catalans in April, just five months after a nasty double fracture suffered against Scotland last November.
"It wasn't supposed to happen again," said Leuluai. "After the Scotland one, there was a metal plate put in there, but it snapped. The doctor said I was very unlucky."
Leuluai's return a month later coincided with an injury crisis at Wigan.
"At times, we had eight or nine first teamers out," said Leuluai. "Sometimes we had young guys thrown in that we hadn't even trained with. But we got through it."
Wigan finished seventh in the regular season, ahead of the Super 8s phase, but more importantly they earned another trip to Wembley.
"It's bigger than the [Super League] grand final," said Leuluai. "There are bus loads travelling down and you are part of history."
Wigan have remarkable Challenge Cup pedigree, with nine victories in 11 years between 1985 and 1995, but less success in the past two decades (three wins in 2002, 2011 and 2013).
"I still remember 2011," said Leuluai. "We got new suits, everyone dressed up and it was an amazing feeling to win it. It would be great to do it again."
Hull broke an incredible Wembley jinx last season, finally winning the Challenge Cup on the hallowed London turf after nine defeats there stretching back more than a century.
"It was crazy," recalled Hull football manager Motu Tony. "When we won the game, it felt like a funeral - so many people were crying. I had fans in their 70s and 80s tell me they never thought they would see Hull win at Wembley in their lifetime and now they could die happy. It meant that much."
Like Wigan, Hull have strong Kiwi connections, with the 1980s quartet of James Leuluai, Gary Kemble, Fred Ah Kuoi and Dane O'Hara, while Tony, Stephen Kearney and Richard Swain featured in Hull's 2005 Challenge Cup success in Cardiff.
"I can't imagine the reaction if we win it again," said Tony. "The celebrations will go on for weeks."
