Kathryn Plummer readily admits that her street smarts don't match her book sense.

"In Palo Alto we were driving one night, and it said 'coin wash' -- you know a laundromat. I thought it was actually a place to wash coins," she says laughing. "I'm a goofball."

"Dweeb" is the word Stanford volleyball teammate Jenna Gray prefers.

"On the court she's so serious and competitive," Gray says. "Off the court, she can make fun out of anything. I like to pop out and scare her, and she gets super, super scared. She'll try to do it back to me, but she'll poke her head out too early and I'll see her."

The other word Gray uses: klutz. Several on the Cardinal football team saw that up close last season when, stepping out of an ice bath, Plummer slid to the floor.

"I got pretty hurt, but it was really funny," Plummer says. "That was my introduction to this place."

The AVCA freshman of the year last season who stands 6-foot-6 displays none of those traits on the volleyball court. Just a sophomore, she's a legitimate candidate for national player of the year coming into the 2017 season. Stanford and Plummer open defense of their national championship on Friday with a date at Long Beach State.

The start of last season was bumpy for a youthful Cardinal team that dropped seven regular-season games. Losses and injuries forced coach John Dunning to abandon his 6-2 offense in favor of a 5-1, a move that involved Plummer switching from opposite to outside hitter. That transition required her to become far more accurate at passing and clutch at hitting.

Plummer relayed the news to her parents during their weekly phone chat. "I'm going to be moving to the left," she said.

Michelle and Kevin Plummer laughed. When Kathryn didn't, they asked, "Are you serious?"

"We thought she was messing with us," Michelle said, noting that she and Kevin would almost cringe when Kathryn rotated left during her club and high school games. "That was not her comfort zone."

Plummer aced the learning curve, hardly surprising for someone still bitter about the lone B she received in high school

"An 88 in AP U.S. history," she groans.

Plummer acclimated to the role quickly and Stanford went on to win 16 of its final 17, including a four-setter over Texas in the title game.

Coach Kevin Hambly, hired when Dunning retired after the season, didn't have a chance to study Plummer until the postseason.

"I thought the move to the left really suited her," he says. "When I watched her play the left, I was like, 'Man, that's the place where she belongs because of her physicality and her size.'"

"Now hitting on the right side feels a little weird," Plummer says. "It's fun to have something that I excelled at last season and now I can continue getting better. It's exciting to see where I could go."

New coach Kevin Hambly has been impressed with Kathryn Plummer's passing and defense. Courtesy Stanford

Athletics always appealed to her, starting with soccer and basketball. She even considered cheerleading, sort of. "I wanted to be a flyer," she says. "My mom stopped that dream."

Still, Plummer enjoyed being a sideline cheerleader for her brother, Kris, four years older and an NAIA national champion in volleyball at Concordia.

During one of Kris' club tournaments in Chicago, 11-year-old Kathryn killed time by batting a volleyball around with another girl her age.

"I remember not being able to hit the ball over the net," she says. "I finally got it and was so excited."

Her brother's coach was impressed. "She's got great hands!" he said at the time.

"She's never done this in her life," Michelle thought, and figured that was the end of it.

Instead, it was the beginning.

Kathryn grew up wanting to be like Kris; the two share a volleyball connection and an offbeat sense of humor.

"They know every line of 'Napoleon Dynamite,' and go back and forth with the dialogue,'" Michelle says. "Nobody else knows what they're talking about."

After just a few clinics at Laguna Beach Volleyball Club, Plummer was invited to play on her first team. She dropped soccer, and to her mother's chagrin, basketball fell by the wayside, too.

Michelle Plummer played hoops for Weber State and admits, "Yes, I cried" when Kathryn told her she wasn't going to play high school basketball. Kris had followed the same path years before.

But it didn't take long for Michelle to recognize that Kathryn had found more than an extracurricular.

Kathryn Plummer landed honor after honor during her freshman season at Stanford. Courtesy Stanford

"It's her passion," she says. "When she started playing volleyball, she always wanted more. 'Can I practice more?' she'd ask. 'Can I go practice with other people?' Anything to get better."

"I love it," Kathryn says. "Whenever I'm playing volleyball, I'm happy. And I don't see a time when I'm not happy. You can get better and learn new things all the time."

Plummer's decorated high school career included being selected Gatorade Player of the Year in California in 2015. That summer she became the only player in history to win FIVB world championship medals in both indoor and outdoor volleyball.

She explored Big Ten options for college, but decided on Stanford, six hours north of her hometown, Aliso Viejo, California. In addition to volleyball, Plummer loves the academic setting, where it isn't unusual for her to be seated next to a brainiac developing a funky new app or a 19-year-old entrepreneur. She's tight with her teammates, many of them members of what she calls a "low-key sorority," Kappa Kappa Gamma. Plummer recently pledged.

As for volleyball, how could it be better?

During much of 2016, it looked like a Big Ten team would be NCAA champion. Nebraska, Minnesota and Wisconsin each held the top spot in the AVCA poll; Washington won the Pac-12 regular season. When Texas knocked the Cornhuskers out of the final four, it looked like the year for the Longhorns.

But sixth-seeded Stanford upset Minnesota in the national semifinals before upending Texas to secure the program's seventh national championship. On the court in Columbus, Ohio, that featured more big hitters than the home run derby, Plummer showed off her explosiveness. Her 30 kills in the final four trailed only Texas' Ebony Nwanebu, who finished the two games with 31. Her 11 double-doubles for 2016 led the Cardinal as did her 3.34 kills average.

The surreal experience of winning a national title produced the traditional dog pile, made even more special given the role the nation's top freshman class produced. Among the six Cardinal true freshmen, four started the title match.

"All five of them are my best friends," Plummer says. "Experiencing this with them is something I'll be able to remember the rest of my life. "

A repeat is more than plausible despite the graduation of All-American middle blocker Inky Ajanaku. Plummer hasn't taken a break from the game, honing her skills last spring on the sand, when she was named Pac-12 beach player of the year. Her summer included a trip to China, where she took home a bronze medal at the FIVB Under-21 beach world championships.

"I want to win every year. I think at a place like Stanford, that's possible." Kathryn Plummer

Hambly already likes what he sees from Plummer in these early weeks of practice, touting her improved passing and defense.

"She moves differently than she did last year," he says. "She's more in the flow of a six-rotation player. I think she's going to be better and better and better and be one of the best outsides in the country. I see her becoming a top-level international outside."

Plummer also credits herself with being calmer this season in practice and navigating the campus that seemed like a gigantic maze a year ago. Stanford is a humbling environment, with so many other championship teams and legendary athletes.

"Honestly winning a national championship at Stanford is expected," Plummer says. "So when you're doing it, it's what you're meant to do. If it doesn't happen, it's about winning it next year."

Now she's pumped to start her next year this week.

Plummer recalls her dad asking her after the team banquet last winter, "What do you think it would be like to go to an awards banquet and not win?"

"I don't know," she responded. "I have no plan on knowing. I don't want to know. I want to win every year. I think at a place like Stanford, that's possible."