When Western Sydney Wanderers striker Lynn Williams was playing for the now-defunct NWSL side Western New York Flash in 2015 – her first season playing professional football – her team finished third from bottom.

It wasn’t that the Flash lacked talent: Williams was joined that season by Wanderers teammate Kristen Hamilton, as well as future World Cup winners Abby Dahlkemper, Samantha Mewis and Sydney Leroux. The club had a history of success, winning the league two seasons earlier with players such as Sam Kerr, Carli Lloyd and Abby Wambach. But they were in a slump; 2015 was a transition year that saw a number of key players depart and several young talents brought in. Finding chemistry on the field was one thing, but after two consecutive underwhelming seasons, the biggest challenge was finding the motivation to get back to winning ways.

Enter new head coach Paul Riley. His tactics and training regimes were complex and exhausting, but Riley’s most important contribution was in shifting the team’s mentality – turning a group unfamiliar with recent success into perennial winners; leaning into their history, not away from it. It is how the phrase “underdog” became a mantra in Riley’s team culture.

And it worked. In 2016, a year after Riley was hired, Western New York made the play-offs and won their first championship title. Williams, who had scored three goals the previous season, won the league’s Golden Boot award with 11 and put away three more during finals. The club folded the following year, but the bond between the players and staff was such that almost all of them stayed together, rebranding as North Carolina Courage. Since their founding in 2017, the Courage have won the premiership-championship double twice. They are the only NWSL side to have done so.

But for Williams, the underdog mentality remains as strong as ever. It is one she and her North Carolina teammates Hamilton and Republic of Ireland international Denise O’Sullivan brought to Western Sydney for this W-League season.

Forged in the hot iron of Riley’s underdog culture, the three international recruits have sparked something special in a Wanderers side that, perhaps more than any other in the league, needed the same psychological upheaval as Western New York had after disappointing recent campaigns.

If you think you have no room to grow, that’s when big teams start to fall Lynn Williams

“If you know the whole story of the team in Western New York, we were godawful,” Williams tells Guardian Australia. “We actually were the underdog; we had no business being in the championship game but somehow we got there. And we had no business winning, but somehow we did that. So taking that mentality of working hard, and when you [start] thinking you’re the best … how do you get better? If you think you have no room to grow, that’s when big teams start to fall. And that’s one thing Paul [Riley] always instils in us: you’ll always have room to grow, you’ll always have something else to work on. And I think that’s where the underdog mentality comes from.”

It couldn’t have arrived at a better time for Wanderers: a club that hasn’t finished higher than sixth in their seven-year history, and whose most recent season was their worst ever recorded, with just a single win to their name. But rather than frightening off potential international recruits, Western Sydney’s status as W-League underdogs was the perfect fit for Williams and her teammates.

“When I told some friends that I was going to Western Sydney, they were like ‘oh god, don’t do it! Don’t do it!’” Williams says. “I was like, ‘why not?’ And they said, ‘they’ve only won one game!’ But I’ve been there before. I’ve been on a team that was so bad and had no business winning. And as long as you get everybody on the same page and people that are willing to work, you never know what could happen.

“If you were to talk to anybody on this team right now, anybody would say ‘we can do it’. For a team to come back and for players to come back year after year after not having success, I think that shows the character of that player. And those are the players that Dean [Heffernan] brought back and brought in a couple new players for a different mentality, and I think right now it’s a good blend.”

Wanderers’ Denise O’Sullivan in action against Canberra United this season. Photograph: Matt Blyth/Getty Images

This mentality shift is having a clear effect on Western Sydney’s performances this season: at the midway point they sit at the top of the ladder and lead the W-League in several statistical categories. Unsurprisingly, the North Carolina trio of Williams, Hamilton and O’Sullivan are at the heart of that success, combining for 10 of the team’s 16 goals while also delivering six assists, 63 shots and 36 chances created, more than any other combination of players in the league.

And although they’ve only been together for eight weeks, head coach Heffernan has noticed what his international recruits have introduced to the playing group.

“For me, watching them work day in, day out, they’re winners,” Heffernan says. “They play and train with a level of intensity that rubs off on everyone else. There’s something driving them – something different – that’s for sure, and it’s rubbing off on our girls as well. And now it’s pointing in the direction of what we want to achieve.

“Even in terms of how we play … it’s a shift in mentality that now everything has to be on the front foot rather than taking a backwards step. So there’s a mentality shift on the field [and] off the field, but it’s more so a belief and a confidence in what you’re doing as well.”

It’s a move that has been complemented by the club’s efforts off the field, too, with increased investment and the completion of the Wanderers’ new training facility in Blacktown – the psychological effects of which cannot be understated, particularly for female players who have rarely felt equally supported by the footballing organisations they have worked for.

Western Sydney’s unprecedented start to the 2019-20 season has already thrown their underdog status into question, but if they are to become to the W-League what North Carolina are to the NWSL, it’s safe to assume that the mentality that has got them this far will continue to drive their successes for seasons to come.