HOUSTON – Josh Willingham didn't sound like a guy desperate to leave Minnesota.

"[I] have mixed emotions," he said after being told he had been traded to the Royals on Monday. "Any time when you're saying goodbye to really good friends, it's tough. But on the other side of it, they're winning over there. From the business part of it, it's a good move for me. I get a chance to win and maybe experience the playoffs, something I haven't been able to do in my career."

And the Twins get a chance to make their roster even younger. Willingham was swapped for righthanded pitcher Jason Adam, the Royals' fifth-round draft pick in 2010. Adam, 23, who posted a 2.35 ERA in eight games for Class AAA Omaha, will report to Class AA New Britain, where he will be converted back into a starting pitcher.

"He's a young kid with a good arm," Twins General Manager Terry Ryan said of Adam, who grew up 20 minutes from Kauffman Stadium. "His stuff is pretty impressive. You look at his bio, his numbers aren't really eye-popping, but we've seen him quite a bit. A number of our people have put in good reports on him."

Willingham's departure, with just two months (and about $1.75 million) remaining on his three-year, $21 million contract, gives the Twins more than just a midlevel pitching prospect. It also frees up a spot on the roster, which was filled by activating Joe Mauer from the disabled list, and at-bats, which figure to go to Kennys Vargas.

Willingham and his $7 million annual salary looked like a tremendous bargain when he smashed 35 home runs in 2012; only one Twin has hit more, Harmon Killebrew. But his career-high .524 slugging percentage that season slipped to .368 last season, a year wrecked by midseason knee surgery, and was only .402 this season, after he missed a month with a hairline fracture in his left wrist. In his final two seasons with the Twins, he hit only .209 in 179 games, and struck out 206 times.

"He had a fantastic first year," Ryan said. "This year, it seemed like he was trying to catch up. But I have no second thoughts about the acquisition of Josh three years ago."

He was patient at the plate, drawing 184 walks (and getting hit by 35 pitches) while with the Twins, but at 35 he was hitting home runs with decreasing frequency. Just like Justin Morneau last August, however, Willingham homered in his final game as a Twin, connecting on a two-run shot in Oakland on Sunday to help the Twins salvage one of the four games there.

When the Royals claimed Willingham off release waivers, Ryan said, the Twins jumped at the chance to move him to a pennant contender. Kansas City has won eight straight games and climbed over the Tigers and into the lead in the American League Central. The Royals will visit Target Field this weekend, and again in September.

"It's been a lot of fun" playing in Minneapolis, Willingham said. "It's a great baseball city, it really is. The fans are good, they love their baseball, and it was a pleasure playing for Gardy and the coaching staff. [I enjoyed] all the relationships, from the owners all the way down to Dom the batboy. My three years here were fun. The only part that didn't happen was we didn't win."

Etc.

• Trevor Plouffe was back in the lineup Monday after sitting out Sunday's game with a swollen left foot. And Oswaldo Arcia, though not in the lineup for a third day in a row, got through batting practice with no recurrence of his back problems, and has avoided a disabled-list stint.