Dwyer had a 10-11 record and a 3.55 ERA, sixth best in the Pacific Coast League, for Triple-A Omaha.
"I thought I threw well, and obviously going to the playoffs and winning the whole thing was special for us," Dwyer said. "And getting called up at the very end was a dream come true."
Dwyer, 25, caught everyone's attention in the Triple-A National Championship game by taking a perfect game into the seventh inning. He didn't get it, but got the victory as the Storm Chasers beat the Durham Bulls, 2-1.
After that, Kansas City called, and he pitched in two games with three scoreless innings of relief.
"Real good breaking stuff, real good changeup," manager Ned Yost said. "He did a nice job when he came to the big leagues last year."
Dwyer throws a fastball in the 88-92-mph range, but his dropping curveball is his primary weapon.
"The curveball, that's the two-strike pitch and the out pitch that I have. When it comes to get somebody out, I use that curveball -- not that I wouldn't use other pitches, but that's my best pitch," he said.
Dwyer will follow James Shields to the mound in the Royals' second Cactus League game against the Rangers.
"He made great strides as a pitcher last year, especially in the second half, and pitched some of the biggest games in that championship for Omaha," Yost said. "He's always had real good stuff and he continues to polish his command."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.