University of Hawaii catcher Kekai Rios’ baseball success is rooted in a square.

Growing up in Kahaluu, Rios turned his backyard into a Wiffle Ball stadium. “I played with my cousins,” Rios said. “I’ve got a decent-sized backyard. It’s more squarish. We kind of created a diamond out of it.”

They pitched a Wiffle Ball — a plastic ball with eight oblong holes on one side to make the throws bend — and hit with a broomstick. Curveballs were not permitted. “We kept swinging and missing them,” Rios said.

And any ball hit over the fence was an out. “That was the main rule,”Rios said. “We always tried to hit line drives.”

That level swing and plate discipline have carried over to Rios’ UH career. This season, his slash line is: .349 batting average, .446 on-base percentage, and .476 slugging. In this past week’s four-game series against Indiana, Rios hit .563 with four doubles. Sunday’s walk-off single would have been a double.

“It was a matter of time before he settled in and starting seeing the ball well,” UH coach Mike Trapasso said.

Rios said he is using techniques learned from a mental-performance specialist who worked with the Rainbow Warriors in the fall. He was taught to take deep breaths and “lock in” on a pitch. “Once that pitch is done, forget about it, and focus on the next pitch,” Rios said. “That definitely helped me a lot.”

An early memory is playing catch with his father when he was 3, spawning his love for the sport. Rios eventually developed a powerful arm, but decided not to use it to pitch. Pitchers do not play every game. “I loved hitting and playing the field,” Rios said. “I wanted to be in every game, so I didn’t want to be a pitcher.”

Playing catcher, he figured, would allow him to be further involved. It was his catcher’s tools — receiving, blocking and throwing — that led to his place on the UH roster. Last season, Rios threw out 31.7 percent of would-be stealers. This year, his caught-stealing accuracy dropped to 27.3 percent.

“That’s one part of my game I’m trying to work on more lately,” Rios said. “Lately, I’ve been struggling with my throws. Slowly by slowly, I’m coming along and finding my groove again. … I got so comfortable last year, I stopped working on that part of my game. It shows now that I’m struggling not throwing out a lot of guys or making that right throw. I like being a defensive guy.”

He has worked on his front-foot placement, which gives him better balance on throws. “I know it’ll come along,” Rios said.

The ’Bows play San Jose State on Thursday evening in the opener of a four-game series at Les Murakami Stadium.