Two months later, the right-hander called his mother again, this time to tell her he was going from Double-A to Triple-A Omaha. The high-fives in the room drowned out the rest of the conversation.
On a Tuesday night in late September, the reliever was on the receiving end of a call from the Royals. A few minutes later, Maria picked up the phone on the first ring.
"'Again? That's great, son. Can you get any higher?'" said Herrera, recalling his mother's reaction. "'The Major Leagues are the highest, right?' Yes, Mom, now I have to stay there."
Herrera's quest to get back to the Major League continues, and he hopes to make at least one more joyous phone call to the D.R. at the end of Spring Training. But in the meantime, he still has work to do. Herrera has already pitched in one Cactus League game and is scheduled to throw on Wednesday against the Padres at the Peoria Sports Complex.
"All I can do is show what I have and what I can do," Herrera, 22, said. "My goal is to stay healthy. If I stay healthy, I can do anything."
Don't mistake Herrera's confidence for cockiness. His words are not meant to be brash. His numbers, on the other hand, are bold and speak for themselves.
Last season, Herrera, ranked No. 8 in the Royals' system, was named the Paul Splittorff Minor League Pitcher of the Year after a combined record of 7-1 with 14 saves and a 1.60 ERA in 45 games for Omaha, Northwest Arkansas and Wilmington.
He made his big league debut in the eighth inning of a 3-3 game against the Tigers on Sept. 21 and had an immediate impact. Herrera hit the first batter he faced, Ryan Raburn, and Miguel Cabrera followed with a run-scoring double. Two batters later, Don Kelly hit a two-run home run.
The Royals lost the game, 6-3, and Herrera was tagged with the loss but remained unfazed. He had long understood the notion that big league hitters rarely miss their spots when pitchers miss theirs, and he had not forgotten that he only pitched a total of 46 1/3 innings in 2009 and '10 because of a stress fracture in his right elbow. Herrera wasn't going to let one bad night ruin a great year.
"He was better in Double-A than he was in Class A, and our Triple-A manager says he's the best reliever he has ever had, and that's saying a lot," said Scott Sharp, the club's director of Minor League operations. "We continued to challenge him, and he met the challenge. We felt that if he would have been healthy, he would have been in Triple-A and on this path anyway."
Herrera's path to the big leagues is not without obstacles. Right-handers Louis Coleman, Blake Wood, Sean O'Sullivan, Vin Mazzaro, Nate Adcock and Luis Mendoza -- unless Mendoza makes the rotation -- along with left-handers Tim Collins, Jose Mijares and Everett Teaford are all competing for a spot in the bullpen.
Only setup men Jonathan Broxton and Greg Holland, closer Joakim Soria and Aaron Crow -- unless he makes the starting rotation -- have secured positions in the bullpen.
Herrera has a chance. Royals manager Ned Yost has repeatedly said that the Royals won't hesitate to shuttle pitchers back and forth between Omaha and Kansas City if someone on the big league staff falters.
"He's got tremendous stuff. He's right in the mix," Yost said. "That's the best I can tell you right now. He's right in the mix of these guys. He's right in that 20-man group."
Herrera doesn't have a problem with competition. He jokes that he might not be the best baseball player in the family. His father, Sebastian, is a former ballplayer and his teenage brother, Edward, hopes to sign a contract with a big league club and enter an academy on the island sometime this summer.
Herrera, who is listed at 5-foot-10, says Edward is over six feet tall and is still not sure who throws harder.
"Dad says there weren't so many scouts or all of the academies in his time and how easy it is to sign now," Herrera joked. "They come looking for us, where before, players went looking for teams. I don't believe him. I think he was just not very good and that's his excuse."
In all seriousness, Herrera credits Sebastian, who works in construction, for teaching him the value of hard work. He wants to be a good role model for Edward and little sister Marybelle, 13.
"My family is so proud of me," Herrera said. "Every time I got closer to my goal, my mother would encourage me not to get complacent. She always said that you have to keep working hard to get the best out of yourself."
Good call, Maria.