Rivero went to Rays camp on Monday and was surprised to learn a few days later that he had been dealt after spending five years in that organization.
"I was shocked. [The Rays] called me into the office and told me that I have been traded," Rivero said. "They told me yesterday, and I was practicing over there. It was pretty hard on me."
There was one consolation, however, with Lobaton part of the trade.
"When I heard that he was traded with me, I was very excited, because I don't know anybody on the team," he said. "I played with him [during Spring Training]. He is one of the guys that I know."
Rivero won a career-high nine games and posted a 3.40 ERA in 25 games (23 starts) last season for Class A Charlotte. He represented the Rays at the Sirius XM All-Star Futures Game at Kauffman Stadium in 2012 while pitching for Bowling Green, and he earned an All-Star nod from the Midwest League. His fastball can hit 96 mph, and he has a good breaking ball.
The Nationals will watch Rivero pitch in canmp before deciding where he will start the season.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the Time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.