"His ball explodes from his hands," Hernandez said about Rivero. "A lot of people are throwing the ball [well]. Cedeno threw the ball [well]. He is a special lefty. It's going to be good when the [exhibition] games start."
When the spring season starts next Friday, Hernandez will continue to lend his expertise to the pitching staff.
"This is more important -- doing this and helping the guys get ready for the season," Hernandez said. "I want to help them put their minds together. In this game, the mind is more important. The mind is 90 percent of the game. When your mind is right, you are going to be good for a long time."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He can be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.