PHOENIX — David Riske spent only a year in Kansas City, but that was enough time to help a painfully shy kid who had lost his way.

In 2004, Zack Greinke showed he had the talent to pitch — and win — in the major leagues at age 20. But a few years later, his career had become a question mark instead of the exclamation point everyone expected.

A loner who walked out of spring training in 2006 for treatment of a social disorder, Greinke was failing as a starter for the Royals last year and was demoted to the bullpen.

Greinke’s troubles reminded Riske of his childhood in suburban Seattle, when his best friend struggled with depression. So Riske, 31, went out of his way to build a bond that helped Greinke turn everything around.

“When you hear about someone like that, especially with that kind of talent, that has a little bit of an issue, it’s sad — it really is,” Riske said. “I just tried to help him out as much as I could.”

Riske signed with Milwaukee in the offseason, but he and Greinke have maintained their friendship. They’ll cross paths again later this week, when the Royals and Brewers play a pair of exhibition games in Milwaukee on Friday and Saturday.

Greinke, who might start one of those games, has had a solid spring and is expected to begin the season in the Royals’ rotation — signs that his career is back on track.

Some of the credit goes to Riske, who had no idea he’d have such a profound effect.

“I just felt like I always saw my best friend in him, and I just felt like I could help him out,” Riske said. “He’s such a great person, too; he’s just quiet. He’s a really good dude.”

Riske’s message as a mentor was simple, but Greinke needed to hear it.

“Just come to the park every day ready to do your job instead of just doing it for fun,” Greinke said. “You’ve got to be mentally ready every day, no matter what. That’s the main thing he brought.”

It worked. Greinke had a 3.54 ERA in 38 appearances pitching out of the bullpen for Kansas City, and the lowly Royals won 25 of those games. When Greinke returned to the rotation, he went 2-2 with a 1.85 ERA in seven starts during August and September.

“I wanted to be that person or that teammate that went out of my way to get him because he doesn’t like to talk a lot or whatever, but I went out of my way to talk to him, get him to talk to me and get to know him a little bit,” Riske said.

Riske helped Greinke understand how he could fall from being a first-round pick in the 2002 draft to admitting he hated baseball and leaving he team for emergency counseling — and how he could ditch all that baggage by simplifying his approach to the game.

“I just tried to simplify it and say, ‘Go out there and be aggressive and go right after people, who cares what happens,’” Riske said. “We really connected. I tried to help him out as much as I could.”

As Riske helped Greinke became dominant again, their relationship began rubbing off on the rest of the Royals’ relievers.

“Without him in the bullpen, we wouldn’t have been anywhere close to what we did,” Greinke said. “We probably would have been a lot more like we had been over the last four or five years, a well-below-average bullpen. And I’m pretty confident that just by his help, we’ll be able to continue the things he taught.”

Now Riske will have a chance to connect with a new bullpen that includes another talented but troubled teammate: Brewers reliever Derrick Turnbow, who was hounded by fans as he frittered away leads last season.

Riske said being a relief pitcher is one of the toughest jobs in baseball, and he’ll try to help his teammates in the bullpen forget bad outings.

“I hate to lose. I hate to fail at anything,” Riske said. “I always say relievers have the hardest job in the game. You have to be perfect every single time out or else you didn’t do your job.”