Trevor Larnach hit three home runs over 88 games during his first two seasons at Oregon State.

Then he worked on his swing. He filled out. Balls began clearing fences all over the Pacific-12.

And that power surge made believers out of the Twins, enough that they took him with the 20th overall pick of baseball’s amateur draft Monday.

Larnach, whose Beavers play host to the Gophers this weekend in an NCAA super regional with a trip to the College World Series at stake, is viewed as a power prospect on the rise, a potential corner outfielder who can provide plenty of pop for the Twins.

In the second round, the Twins selected another college player, catcher Ryan Jeffers from North Carolina Wilmington. The 6-2, 220-pound Jeffers has power potential, but evaluators aren’t sure if he will stick as a catcher.

Larnach’s transformation into a legitimate power threat took place during the offseason.

“As the offseason goes on, you have about six months before the seasons starts and that’s quite a lot of time to work on some stuff,” Larnach said. “And there’s an individual who’s name I can’t say who I’ve been working with. It was an every night thing during the offseason. We worked on everything, from the approach to mechanics, which was the most important part as far as allowing that power to play in the games.

“I’ve done everything to changing my batting stance, getting into my back hip a lot more, using my hips, working on the load, working on the gather. So much different stuff that I’ve learned. There’s still even more stuff that I still need to do. I’m not done yet. This is still one stage of my life.”

Larnach said those sessions went as late at 11 p.m. some nights, as he worked to perfect his craft.

Twins scouting director Sean Johnson watched Larnach go off at the Sanderson Ford College Baseball Classic Feb. 16-19 at Surprise, Ariz. That’s when Larnach, a lefthanded hitter listed at 6-4 and 205 pounds, opened eyes.

“We saw him hit some long home runs to center field, to the opposite field and left,” Johnson said. “And that’s when he kind of got on our radar for our pick 20 slot.

“He’s taken a step forward. I think going into the year he was probably not in the conversation. He’s certainly has performed to get himself into the first round.”

Larnach is hitting .327 with 17 home runs and 65 RBI in 58 games for the second-ranked Beavers. He is the 27th-ranked prospect according to Baseball America.

The Twins project him to be a corner outfielder, with enough range to do a solid job. His arm is considered average. But it continues to get stronger after injuring his elbow while dunking a basketball while at College Park High School, in his hometown of Pleasant Hill, Calif.

Johnson said the Twins blended analytics with what the scouting reports revealed. Larnach’s launch angle is low, but his exit velocity was among the highest in the country, based on stats provided by stadiums that have installed the TrackMan baseball system.

His exit velocity was higher than outfielder Brent Rooker’s was in college. And the Twins drafted Rooker, the promising first baseman-outfielder now at Class AA Chattanooga, with the 35th overall pick last year.

“He’s somewhat of a college player who hasn’t hit his full ceiling yet,” Johnson said. “His body has gotten bigger and stronger. His body has filled out. His raw power has taken another step forward this spring. Obviously he has performed at a high clip. We are certainly excited to have him.”

Johnson said that the Twins already have the framework of a deal in place with Larnach and expect to sign him shortly after his college career is over. The assigned value of the 20th pick is $3.1 million.

The Gophers can expedite that signing this weekend. Larnach, of course, wants a longer run in the postseason. But he can’t wait to begin his Twins career.

He is excited to be selected in the same round as college teammate Nick Madrigal, a shortstop who was selected by the White Sox fourth overall.

“Expectations were all over the place,” Larnach said. “I was pretty stressed on where I was going, who was getting picked. I couldn’t wait any longer.”