Both players, who were given the news by Rizzo and manager Jim Riggleman, will start the season with Double-A Harrisburg. Rizzo said both players need more seasoning before they make their first appearances in the big leagues.
"It was for the benefit of their development," Rizzo said. "They needed some time to refine their tremendous skills. Both conversations went well. Both players are competitors. They are disappointed they didn't make the club, but understood the rationale."
Strasburg, the No. 1 overall pick in the 2009 First-Year Player Draft, received the news a day after he gave up two runs in four innings and struck out eight Cardinals at Space Coast Stadium.
Though Strasburg was arguably the best pitcher in Washington's Spring Training camp, giving up two runs on eight hits while striking out 12 and walking just one in nine innings over three spring starts, his success never changed Rizzo's thinking.
"I'm not a believer that a player can come from amateur baseball and step right into the Major Leagues," Rizzo said. "I've seen terrific prospects attempt it, and the failure rate is too great. This is a prized asset. We have to do what's best for the player and for the organization, long-term, and I think the best way to do it is getting some seasoning in the Minor Leagues."
Strasburg, who showed no emotion after getting the news, said he was never told anything about his future until his last few days in Major League camp, but he still thought he had a chance to be in the rotation.
"I knew how much time I had up here," Strasburg said. "I just wanted to come up here and get the work in. I did what I had to do. Hopefully, I impressed the people who make the decisions. Hopefully, I'll be back soon.
"They didn't tell me anything until toward the end of camp. There [was] always that thought in my head [that I would be on the Opening Day roster]. Everybody is competing for a job here. I felt I was included, but it's all good. I'm going down to Harrisburg and [learn] what I need to learn. I'll be ready to get called up -- hopefully, soon."
The team believes Strasburg has a lot to learn, such as holding baserunners, fielding bunts and getting better when it comes to pitch selection.
"Sometimes it will not make sense," Strasburg said. "More times than not, it's going to work out in the long run. I trust what they are doing with me. I'm going to do what they tell me."
Perhaps Strasburg's biggest highlight with the Nationals this spring occurred off the field, when Ryan Zimmerman invited Strasburg and his wife to Disney World.
"We were treated like VIPs. That was the highlight for me -- to have some sort of connection," Strasburg said. "Baseball is great, too."
Between Strasburg and Storen, it was Storen, the 10th overall pick of the 2009 Draft, who was thought to have the better chance of starting the season with the big club because of his experience in the Minor Leagues last year. But after experiencing less than stellar outings in his last two appearances, the Nationals decided that he needed more seasoning.
"It's one of those things where there's a big picture to keep in mind," Storen said. "I understand that's part of it. Then you go down, develop a little more and, hopefully, get the callup.
"I didn't feel that I was hit around that much. I just got myself into trouble. So I'm real satisfied how it went. No regrets with the whole thing."
Storen said if he learned anything about Major League baseball, it's that one has to put in a lot work in the weight room and during practice in order to be successful.
"It takes a lot of work off the field," Storen said. "You see what other guys are doing and why they have been successful."
The moves left the Nationals with 39 players in their big league camp.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.