Wave striker Alex Morgan and coach Casey Stoney embrace after the team's playoff-opening win. (Orlando Ramirez/USA TODAY Sports)

Sixteen months ago, the San Diego Wave were created. On Sunday, with an overtime goal from Alex Morgan, they advanced to the semifinals of the NWSL playoffs.

In their first season of existence, the Wave have not eased in. Instead, the San Diego squad established itself as a contender early, and with Sunday’s win, that status was cemented.

Coach Casey Stoney got things going in San Diego by signing a pair of U.S. women’s national team stars in Morgan and Abby Dahlkemper. Then she drafted Naomi Girma out of Stanford and went about crafting a roster.

Yet while Stoney created a strong base, it’s been the camaraderie among players and the winning culture fostered by the coach that has made the difference.

Sunday’s overtime win got off to a rocky start when goalkeeper Kailen Sheridan made an uncharacteristic mistake that led to an early goal from Yuki Nagasato and a 1-0 lead for the visiting Chicago Red Stars.

The Wave responded by containing Chicago for the remainder of the match, getting an equalizer from Emily van Egmond in the 67th minute, and finally winning on a Morgan goal in extra time.

According to Morgan, the way her teammates responded after Sheridan’s miscue highlights what has made the Wave special this season.

One by one, the Wave players approached Sheridan and put her mind at ease.

“We’ve got you. We are getting back in this game. Don’t even worry about it.” Those were the messages Morgan and her teammates conveyed to their goalie.

“I think that support of each other is something that maybe a lot of people don’t see,” she said. “And sometimes you don’t really get the opportunity to play on teams like that. So I think that’s really what sets this team apart.”

That attitude starts with Stoney, who is experienced as both a player and a coach. She spent nearly 20 years playing professional soccer and for her home country of England. Then Stoney moved into the coaching ranks, starting with Manchester United and then taking the job with San Diego.

Through her long and successful soccer career, Stoney learned what qualities matter in a coach and how those traits rub off on players.

“I think you have to show vulnerability yourself first as a head coach,” she told reporters Sunday. “You have to be prepared to show that you are gonna own your own mistakes. You have to create an environment every day where you live and breathe that, and you have honest conversations. And if you get it wrong – and I’ve got it wrong quite a few times with different players this year – you say sorry. … When I make mistakes I own it.”

Stoney’s ability to remain humble and vulnerable worked in the Wave’s favor throughout the season, and they entered the playoffs with the No. 3 seed and a home game against the Red Stars.

Next up, San Diego takes on the No. 2 seed Portland Thorns in the semifinals on Oct. 23 for a chance to play in the NWSL Championship game.