Morillo, 23, struck out 132 in 27 starts at Double-A Tulsa last season and received one Major League start. He gave up seven runs and eight hits in four innings of a game the Rockies eventually won, 9-8, over the Braves at Coors Field last Sept. 24.
Throughout Morillo's career, the Rockies have considered moving him to the bullpen, but he has displayed starter's stamina and coaches wanted him to get plenty of repetitions to hone his delivery. But the bullpen would be his best opportunity to make the team this spring. If he doesn't make the team, the door is open to him pitching as a starter in the Minors.
"It has no bearing after Spring Training -- this just gives him one thing to focus on," Rockies manager Clint Hurdle said.
To become a big-leaguer in either role, Morillo will have to improve his control. He has totaled 233 strikeouts in the Minors over the past two seasons, but he led two leagues in walks and handed out 158 free passes. However, last season inning-leadoff batters hit just .188.
Morillo has not appeared in relief in the Minors since 2002. After last season, he made two relief appearances in the Dominican Winter League, but he backed out of the league because of elbow inflammation.
"I'd always heard that I might end up being a reliever," Morillo said. "I'm not worrying about that. I'm just doing my job."
Extra opportunities: The Rockies have added a couple of "B" games with the White Sox to their Spring Training schedule, on March 5 at Tucson Electric Park and March 8 at Hi Corbett Field. "B" games take place during mornings and are done before the formal Spring Training games. The Rockies also have an intrasquad game scheduled for March 2, since there is no game scheduled for that day.
Such games can give the staff an extra opportunity to evaluate players, especially pitchers.
Statistics (may or may not) lie: Hurdle said the Opening Day starter decision will not be based strictly on statistics or performances in Spring Training games.
Right-hander Aaron Cook, left-hander Jeff Francis and right-hander Rodrigo Lopez are candidates.
"It won't be statistical as far as what they do in Spring Training," Hurdle said. "I just think it'll be some developmental things we're looking at, some challenges we've issued early to each one of them individually."
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.