But Christensen, a 23-year-old left-hander, rebounded to go 5-0 with a 2.87 ERA in six August starts. He finished the season 6-6 with a 4.89 ERA and struck out 153 in 162 innings, while walking 58.
"The first half I was struggling," Christensen said. "I was pitching too much over the middle of the plate. The second half things went a lot smoother."
So smooth that when right-hander Luke Hochevar was shut down early in the Arizona Fall League with a tender shoulder, Christensen replaced him on the Grand Canyon roster. In five games, including two starts, with the Rafters, he had a 1.80 ERA and held opposing hitters to a .194 average.
Christensen's performance, plus adding mileage to his fastball in the well-scouted AFL, led to him being placed on the 40-man Major League roster.
"He was 85-88 (mph) as long as I've seen him," said Art Stewart, a senior advisor to the Royals general manager, who saw Christensen last November in Arizona. "He ended up working at 90 down here, had a plus curveball and an average changeup. He's not ready for the big leagues, but he's ready for Double-A."
Stewart said the Royals "absolutely" wanted to protect Christensen from the Rule 5 Draft in December.
"With the way pitching is today, we weren't going to take a chance of losing him," Stewart said. "He is finally healthy."
Christensen pitched only three innings for Burlington (Iowa) in the Midwest League in 2004 before needing Tommy John elbow reconstruction surgery, which was performed by Dr. James Andrews.
"It just kind of happened on one pitch and that was it," Christensen said. "My elbow was a little sore before but nothing out of the ordinary."
He went to see Dr. Steve Joyce, the Royals' team physician, in Kansas City to have his elbow checked, which led to the reconstructive surgery.
"I knew my season was over after that," Christensen said. "There's nothing else you can do. You don't pick up a baseball for four months."
Christensen began the lengthy rehab process in Surprise under the auspices of rehab coordinator Dale Gilbert, but he never thought his career might be over. "I was only 20 when it happened," he said.
"Last year my elbow didn't bother me at all," Christensen said. "It was just getting the feel of pitching again."
Christensen threw 176 innings last season, including the California League playoffs and the AFL, proving his elbow is sound.
Christensen, a fourth-round pick in the 2002 First-Year Player Draft out of Brooklyn's (N.Y.) Xaverian High School, will likely open this season with Double-A Wichita in the Texas League.
"He had a good Arizona Fall League," said J.J. Picollo, Royals director of player development. "His command of his pitches was good against that (high) level of competition. That [means] the next step would be Double-A."
Alan Eskew is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.