The loss at Peoria Stadium in Peoria, Arizona, was only the third for the Royals in 10 spring games.
The Mariners got to Duffy in a hurry. The first two batters he faced, Dylan Moore and Ty France, hit home runs, followed by a Kyle Lewis triple and Evan White sacrifice fly to make it 3-0. A walk, double and single accounted for two more runs in the second.
Duffy pitched a 1-2-3 third inning to finish with a line of five runs, six hits and one walk allowed over three innings.
Right-hander Tyler Zuber replaced Duffy and allowed a run in the fourth on a sacrifice fly after he had given up a single and two walks to load the bases.
The Royals collected only seven hits, including two with two outs in the fourth on Salvador Perez‘ single and Soler’s blast to left-center field. Perez finished with two singles in three at-bats, the Royals’ only multi-hit effort of the day.
Kansas City scored a run in the ninth after loading the bases on a single, an error and a walk, but Bubba Starling grounded out to end the game.
The Royals will host the Cincinnati Reds at 2 p.m. Wednesday, a game that will be televised by FOX Sports Kansas City.