Sirens forward Casey O’Brien had a tough start to her PWHL career. She felt like her game was misunderstood.

The 2025 No. 3 overall pick, coming off a women’s college player of the year campaign at powerhouse Wisconsin, viewed herself primarily as a playmaker, someone whose vision and passing ability created offense for her teammates.

But coach Greg Fargo and his assistant Josh Sciba told her they wanted her to hold the puck more and look to create for herself.

O’Brien was goalless as the calendar neared the end of 2025. She was frustrated. Her teammate Kristýna Kaltounková, the 2025 No. 1 overall pick, joined the choir in encouraging her to shoot the puck.

With the Sirens playing in Dallas for a PWHL Takeover Tour stop on Dec. 28, an annoyed O’Brien decided she had enough.

She tried to make a play on the puck, but was unsuccessful. Kaltounková told her not to get discouraged.

Then, on her next shift, O’Brien scored her first PWHL goal. She went on to light the lamp two more times that day for her first hat trick.

Each time she skated back to the bench, Kaltounková greeted her with a smirk and an “I told you so.”

That game was a tipping point for O’Brien. Her trust in the coaching staff had been cemented. Her confidence soared.

She went on to lead all PWHL rookies with 22 points (seven goals and 15 assists). She finished second only to Sarah Fillier on the Sirens in points.

O’Brien found out last month that she was a finalist for Rookie of the Year and will learn at the PWHL awards show Tuesday whether she beat out Montréal defender Nicole Gosling and Boston defender Haley Winn for the award.

For most players, being named a finalist for Rookie of the Year would be a season-defining achievement, a way to qualify a player’s first season as a resounding success.

For O’Brien, though, that individual recognition doesn’t erase the disappointment of falling short of the playoffs.

“It’s definitely hard not to look back on the season and be disappointed by it, just because we’re not playing in the playoffs,” O’Brien told The Post last month. “That was the ultimate goal.

“My biggest expectation was I want to make playoffs. Since we didn’t achieve that goal as a team, it’s hard for me to look back on this season as a success for myself because so much of my individual markers on my success is how well the team does.”

O’Brien wants to win with the Sirens for her city.

O’Brien grew up in SoHo and spent countless hours commuting to hockey practices in New Jersey. She remembers waking up before dawn for 6 a.m. games at Chelsea Piers and idolizing the Rangers.

One of her favorite memories came at age 7, when she skated during an intermission at Madison Square Garden.

Years later, during the Sirens’ historic April home game at MSG, she stood on that same ice as a professional player.

“When they announced me, ‘Manhattan’s own, Casey O’Brien,’ I almost started crying,” she said. “I would love to go back and tell my younger self that I’d get the opportunity to play my own professional game there one day.”

O’Brien’s impressive rookie season has established her among the league’s brightest young stars. But she’s already looking ahead to what’s next.

O’Brien received a qualifying offer from the Sirens, who protected her rights in Phase 1 of the PWHL expansion process in early June.

The missed playoff opportunity still lingers. The Sirens remained in contention until the second-to-last game of the season, leaving O’Brien replaying key moments.

One game in Detroit stands out, when she failed to convert on two breakaway opportunities in a loss.

“If I score on either breakaway, maybe we win,” she said. “You look back on how one play or a couple plays could change the entire outcome of the season.”

The frustration has fueled her offseason training. O’Brien plans to focus on finishing chances, improving breakaway moves and capitalizing on rebounds around the net.

“It’s so motivating because the first thing I’m looking at now going into the offseason is what can I do to be someone who in those big moments next year [capitalizes],” O’Brien said. “I’m going to make sure that I’m converting, I’m going to make sure I’m making the play that in the moment it might not feel like it’s the season on the line. … I’m going to make sure that I’m going to be finishing my individual chances next season.”

If she accomplishes that, more individual accolades could be heading her way.