Kathryn Plummer is 6 feet, 6 inches of volleyball menace.

The player on the other side of the net who gets in the way of a Plummer kill does so at her own peril.

Stanford setter Jenna Gray usually plays on the same side as the two-time All-America outside hitter in practice, and she’s glad for that.

“I’ve tried blocking her — you know you’re going to get hit hard,” she said. “I’ve seen people get hit in the head.”

Plummer, a junior, has led the Cardinal (24-1, 16-0 Pac-12) to the No. 2 ranking in the country. Stanford’s one loss came at the hands of top-ranked BYU, which carved out a five-set win over the Cardinal in Provo, Utah, on Aug. 31. Stanford hasn’t lost since then and has won 31 straight matches at Maples Pavilion, the longest home streak in the nation.

“We went in not ready for the environment,” Plummer said of the BYU match. “It was insane. That’s what we want to have volleyball be everywhere.”

The loss was good for the Cardinal, she said. “That BYU match sparked something in us, and it’s been smooth sailing ever since.”

Comfortable at home No. 2 Stanford (24-1, 16-0 Pac-12) has won 31 straight matches at Maples Pavilion, the longest home streak in the nation.

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They beat No. 17 Oregon 3-1 on Thursday and thrashed Oregon State 3-0 on Friday.

“Maples is starting to get a little rowdy, which I love,” Plummer said. “The environment’s great. Our freshman year — I don’t know why — it was kind of boring here. Now it’s really fun to play here.”

Stanford fans eventually warmed to the occasion in Plummer’s freshman year when she and the rest of the heralded incoming class helped win the national title in retiring head coach John Dunning’s final season.

Plummer was the American Volleyball Coaches Association’s national freshman of the year and last year she was national player of the year, although Stanford lost in the NCAA semifinals to Florida. She could repeat this season, although history isn’t on her side: the last back-to-back player of the year was Stanford’s Logan Tom in 2001-02.

In a match, Plummer’s strength and skill are readily apparent. But to Stanford’s second-year head coach, Kevin Hambly, “It’s her skill that makes her special. She can pass. She can defend. She can block. She can attack. She has all the shots.”

She didn’t used to have all the shots, he said. “Her first year, she was more of a hitter of the ball. It was all cross-court, all power.”

Like a pitcher who used to rely solely on his fastball, she has added off-speed deliveries. In a match at Oregon, the Ducks were taking away her power, so she sent off-speed shots to the middle of the court.

“She’s been working hard on that,” Hambly said. “She’s as skilled as she is physical. Most players just rely on their physicality.”

Plummer is a student of the game, regularly watching men’s international matches on video, looking for nuances she can use.

She’s a human biology major and hopes to be a physical therapist, but she’s also a student of war and history. Her favorite book is “American Sniper,” the autobiography of Chris Kyle, the deadliest marksman in the U.S. military history. He was highly decorated for four tours in the Iraq War only to be murdered after his military career by a veteran he tried to help.

Plummer also read his widow’s memoir. Heart-wrenching stories affect her very deeply.

In fact, Gray said, “The weirdest things make her cry — like watching a video of Michael Phelps’ career.”

Hambly said, “She probably cries more than any kid I’ve ever coached. Not after a loss. But ask her about Uganda and moms there, she’ll start crying. She’s got a big heart.”

Her mother, Michelle, said she “sees things from the other person’s perspective. She’s been that way since she was very young. She gets teary and emotional; that’s her nervous relief.”

Michelle, a former Weber State basketball player, is 6-3. Her husband, Kevin, a former football player, is 6-8. Kathryn’s older brother, Kristian, is 6-7. He played on an NAIA national championship volleyball team at Concordia in Irvine.

When Kristian played for the Balboa Bay Volleyball Club in Orange County, the family brought 10-year-old Kathryn to a tournament in Chicago. During a break, the club coach, Rich Polk, invited her onto the court.

“Let me see your hands,” he said. “You have meaty paws.”

She remembers thinking of the techniques he showed her, “This is really cool. I want to go to some clinics.”

Plummer eventually dropped basketball — to her mom’s disappointment — and soccer to concentrate on volleyball. She played for the Tstreet Volleyball Club in Irvine and was a four-year star at Aliso Niguel-Aliso Viejo.

She helped the U.S. Under-17 team win gold in beach volleyball at the FIVB worlds in Acapulco, Mexico. In the indoor game, she and the U-18 team won silver at the worlds in Lima, Peru, in 2017. Between indoor and beach volleyball, she also left her mark on countries beginning with “C,” playing in China, Cyprus, Costa Rica and Canada.

Along the way, she heeded her mom’s dictum: “If you’re tall, stand up straight and carry it. People will notice how beautiful you are. If you slump, they’ll think you’re not proud of yourself.”

Hambly thinks she can play for the senior national team, although it will be extremely difficult.

“A lot of players are talented but when they get in that gym, they don’t have what it takes to be the worst player there,” he said. “Because she’ll be that when she goes in, with the outside hitters. These guys are 30-32 years old. They’ve been playing at a higher level than she’s seen for a long time.

“I believe she has that in her to do that.”

Tom FitzGerald is a San Francisco Chronicle staff writer. Email: tfitzgerald@sfchronicle.com Twitter: @tomgfitzgerald