De La Rosa pitched in a Minor League intrasquad game and went five innings, giving up four hits and three runs. Most importantly he walked none and struck out five.
Command has been a recurring issue for De La Rosa so the ability to throw strikes was a plus as he competes for a spot in the Royals' rotation.
The Royals also announced a Minor League trade, obtaining right-handed pitcher Brad Salmon from the Cincinnati Reds for a player to be named.
Salmon, 28, pitched in 26 games for the Reds last season with one loss and a 4.13 ERA. He had 22 strikeouts in his 24 innings.
He also pitched in 37 games for Triple-A Louisville with a 2-2 record, four saves and a 3.56 ERA. His Minor League record for 325 games (77 starts) is 50-40, 4.12 ERA.
The deal has no effect on the Royals' 40-man roster.
After the open date, the Royals resume their Cactus League schedule at 8:05 p.m. CT on Thursday against the Milwaukee Brewers. The game will be televised by FSN-Kansas City.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.