CORVALLIS — Jim Dietz knew where Jake Thompson had been and where he was going.

When Dietz retired to Florence after 31 years as baseball coach at San Diego State in 2002, he started up an American Legion program to help players from smaller high schools like the ones he coached early in his career at Crow, Lowell and Pleasant Hill get recruited by major college programs.

One of the first kids he targeted was Thompson, a three-sport star at Siuslaw High who was uncertain of his future in athletics.

“I knew I had something special in Jake, but I had to get him in situations where people would see him,” Dietz said. “The problem in the small schools is that the big colleges never recruit them unless they can be showcased. There are usually one or two good athletes in every small school, and I know that if they can hold their own against good competition, the larger schools will recruit them.”

Thompson played for the Three Rivers Sandblasters Legion team before Dietz took him to play for him in an Alaska summer league composed mostly of college players.

“I wasn’t really sure if baseball was my sport until the middle part of high school. The game was still pretty new to me,” Thompson said. “Once I knew I was able to compete at that level was when I started to focus on it. Coming from a small school, you don’t get many athletes to Division I schools, so you don’t expect it.”

Oregon and Oregon State each recruited Thompson, and he picked the Beavers before his senior season at Siuslaw.

The 6-foot-2 right-hander has emerged as one of the top pitchers in the nation and is rising up major league baseball draft charts as the Sunday starter for the top-ranked Beavers (38-4, 21-3), who are headed to PK Park for a three-game series against the Ducks (26-18, 9-12) beginning today.

Thompson, a redshirt junior, is tied for the NCAA lead in victories at 10-0 and ranks fifth with a 1.20 ERA. He has a 1.12 ERA in conference games and OSU is 8-0 in Pac-12 games he started.

Thompson was named national pitcher of the month in April by the National Collegiate Baseball Writers Association after going 4-0 with a 0.71 ERA.

“Coming out of Siuslaw and he’s beaten every Pac-12 team,” Dietz said. “UCLA, Arizona State, Arizona, that’s pretty impressive.”

Thompson had a 4.62 career ERA entering this season and went 3-3 with a 4.28 ERA as a sophomore when he moved into the weekend rotation.

“It’s not even the same guy as it was last year,” OSU coach Pat Casey said after a recent outing.

Dietz, who now scouts for the Padres, said the difference is clear to see.

“The biggest transformation I’ve seen is confidence and that comes from maturation,” he said. “It took him a few years to really settle in when you go from Florence, Oregon, with one of the worst baseball fields in the country to Oregon State, coming off a couple national championships.

“If you’re not playing right away after being a superstar at a smaller school, you show up at Oregon State and see all those big guys that get publicity.”

Thompson has not allowed more than two runs in a game this season and has allowed 50 hits in 12 starts.

“My mindset and mental game overall are different,” Thompson said. “I’m playing with more confidence and have more of a plan mentally when I go out there. The physical abilities have been there, so I’m working more on the mental part.”

Thompson was picked by the Chicago Cubs in the 34th round of the major league baseball draft in 2013, but decided to attend college.

“I didn’t feel like I’d learned enough about the game,” said Thompson, who has earned academic honors with a 3.60 grade-point average in economics. “I definitely had to consider it, but I felt ready to go to college and not quite ready for pro ball.”

Thompson will go much earlier when he gets drafted again next month. He is ranked as the No. 85 prospect in the draft by Baseball America.

“I played with Michael Conforto and saw when the scouts were swarming to watch him take batting practice,” he said of the New York Mets outfielder drafted in the first round out of OSU in 2014. “They’re there, but you don’t notice it. Just stay focused on what you do.”

Thompson, who was eligible to be drafted last season but was not selected in 40 rounds, will have bargaining power in negotiations with the option to return for one more season at OSU.

“I’m happy to see him grow up and mature and get confidence in himself,” Dietz said. “He changed his delivery and smoothed out some things and he doesn’t have as many moving parts now, which has made him better. Jake hides the ball longer so you can’t pick it up as well. He’s consistently in the 90s, and that’s a big plus, too. He’s going to get drafted, and I think he’s going to have a good future.”

Thompson has become the success story from a small town that Dietz set out to find in retirement.

“It was all new to me, so it was huge to have Jim,” said Thompson, who consulted with Dietz about recruiting and the draft during high school. “I definitely couldn’t have done all I’ve done without him guiding me through.”