DeWanna Bonner, center, and her Phoenix Mercury teammates feel confident for the WNBA playoffs, which begin Sunday for the Mercury. (Photo by Marvin Forbes/Cronkite News)

PHOENIX – With the WNBA playoff picture all but squared away, the Phoenix Mercury stand just three series away from their first championship victory since 2014.

After wrapping up the regular season with Thursday’s away game against Dallas, Phoenix launches its postseason bid Sunday when the Mercury host the defending champion New York Liberty after securing the No. 4 seed in Tuesday night’s 88-83 loss to the Los Angeles Sparks.

Despite a late-season losing skid, the Mercury still carry optimism into mid-September thanks to a six-game win streak that helped clinch their playoff berth.

The Mercury’s success this season, following their second-worst record in franchise history in 2023, has materialized from the transformation of the team’s core following the departure of Brittney Griner, Diana Taurasi and Sophie Cunningham.

The franchise’s roster renovation came through the acquisitions of four-time All-Star Alyssa Thomas and two-time All-Star Satou Sabally, in addition to re-signing Kahleah Copper, the Mercury’s leading scorer.

Hailed as the new “Big 3,” the trio of offseason acquisitions have propelled Phoenix into contention in coach Nate Tibbetts’s second year at the helm. The underlying “it factor,” nevertheless, has been the allocation of minutes to the bench and their ability to hold their own.

In Tuesday’s game, Tibbetts deployed his entire bench in the fourth quarter. A minimal-risk decision revealed the full power of Phoenix’s reserve, a strength the Mercury will maintain heading into Sunday’s best-of-three series against fifth-seeded New York with a clean bill of health up-and-down the roster.

“My hope is this can give them a little bit of life and energy to just stay ready,” Tibbetts said. “You just never know what’s going to happen, but to play them at the level that they did to only be outscored three points by their starters gives a lot of credit to them.”

The transformation of Phoenix’s defense has separated the Mercury from the competition and years past. Phoenix’s net rating of +4.1, the fifth-best mark in the WNBA, has been in large part due to the team’s lowest defensive rating since 2015 (102.0).

Mercury forward Natasha Mack has been a key piece to the defensive puzzle by leading the team with 78 offensive rebounds and 52 blocks, a large contributor to Phoenix’s 78.2 pace, the third-best mark in the league.

Mack, who was absent from the WNBA scene for three years before signing with the Mercury, has solidified her status as a defensive star and an important factor in Phoenix’s ascension to power.

“She just impacts winning with her efforts on the glass,” Tibbetts said. “You want good things to happen to good people, and she’s stayed with it.”

On the other side of the court, the offense has been more than just sufficient. It’s been record setting.

In the third quarter of Tuesday’s game, Thomas collected her eighth triple double of the season, the highest single season mark in WNBA history. Ahead of the historic moment, dozens of purple signs were raised across the arena, advocating “AT for MVP.”

Thomas’ performance came just one game after she reclaimed the all-time assists record from Indiana’s star forward Caitlyn Clark in the Mercury’s 87-84 loss to the Connecticut Sun.

As a combined unit, the offense has outscored their opponents 3,567-3,428 (+139), a product of their ability to tally 3-pointers at a 33.8% clip with Thomas’ work in the paint, a side of her game in which she takes the most pride.

“I think it’s a lost art,” Thomas said. “Everyone’s always focused on the offense and scoring, it’s the flashy part of basketball. But for me, it’s about getting an open and easy shot for my teammate.”

The Mercury’s success has caught the attention of the Valley and the country under the WNBA’s increased spotlight. Phoenix recorded its 17th sold-out crowd of the season on Tuesday, an environment led by the rowdy X-Factor and one that should be another advantage for the Mercury in the playoffs.

“They’re so loud,” said Sabally, who dropped 24 points in Tuesday’s loss. “Whether we win or lose, people stay at the games and it’s been really a tremendous season.”

With elite team chemistry on both sides of the ball and home-court advantage in Sunday’s first round, the Mercury have a strong chance to make a run in this year’s playoffs. Nevertheless, the road there will be full of trials and tribulations.

Third-seeded Las Vegas, No. 2 seed Atlanta and top-seeded Minnesota have accounted for nine of the Mercury’s 17 losses, an indication that tougher times could be on the horizon.

Phoenix and Minnesota share the same side of the bracket, and fans will recall the Mercury’s swift exit in last year’s first-round bid came against Napheesa Collier and the Lynx’s relentless offense.

New York will prove to be challenging as well. Though the Mercury finished the season 3-1 against the defending champs, the Liberty have retained valuable postseason experience from players like Breanna Stewart and Jonquel Jones.

For now, preparation and focus will be at the forefront of the Mercury’s agenda, as the playoffs present entirely different challenges for inexperienced and experienced players alike.

“Everyone that’s been in a postseason like that knows it’s another level of basketball,” Thomas said. “Most players have to take their game to even another level. But I think we’re doing a great job of preparing for the playoffs.”