"We'll see what happens," Moore said. "This game changes day by day. We felt we really needed to add some depth to the rotation. He gives us that.
"But as of right now he'll be on the team out of the 'pen."
Young, 35, was signed to a one-year deal for $675,000, but with potential performance and roster bonuses that amount could surpass $5 million. There is no opt-out clause to the deal.
The Royals have long admired Young, who is 6-foot-10 and was The Sporting News' comeback player of the year after going 12-9 with a 3.65 ERA for the Seattle Mariners last season.
"He has tremendous makeup," Moore said.
Young missed the 2013 season after having surgery to correct the effects of a congenital condition known as thoracic outlet syndrome, a nerve condition that can affect the use of the upper limbs.
"I feel great now," Young said. "Best I've felt in a long time."
Young was terrific for most of 2014, including two superb outings against the Royals in which he gave up just six hits and two runs in 15 innings.
But Young faltered down the stretch -- he had an 8.35 ERA over his last five starts.
"Fatigue was a factor," Young said. "I geared up when my season started Feb. 14 to try to make the team. I paid the price late in the year. ... It was unfortunate timing. As a staff we got cold at the wrong time. And I let the team down so we wound up watching the Royals in the playoffs."
During his 10-year career, Young has pitched only one game out of the bullpen and that was last season.
"Pitching is pitching," Young said. "I'll be fine with it."
Jeffrey Flanagan is a reporter for MLB.com. Follow him on Twitter at @jflanagankc. This story was not subject to the approval of Major League Baseball or its clubs.