Released by the Royals at the end of Spring Training in 2009, he signed with Colorado and was called up by the Rockies last May.
"I was doing really, really good and I was the setup man for a couple of months. It was my best time ever and they gave me a great chance to be there," Peralta said.
But he struggled at the end of last season and became a free agent. He signed with Washington for 2010 and was sent to Triple-A Syracuse, where he piled up impressive numbers as the closer -- 20 saves in 20 opportunities, a 1.08 ERA and 38 strikeouts with only seven walks in 33 1/3 innings.
"I've been trying to focus a little more on pitching down and in more than before, and that's been helping me," Peralta said. "But the velocity's is just the same."
He made his Nationals debut on Tuesday night against the Royals and got Jose Guillen to rap into an inning-ending double play.
Now that Peralta is in the National League, he might have a chance to hit. After all, he had a memorable two-run double for the Royals on May 20, 2007, in an Interleague game at Colorado. That hit came in the 12th inning, as the Royals broke a 5-5 tie and Peralta nailed down the victory with a scoreless inning in a 10-5 win.
"I'll tell you what," he said, grinning, "I hope I don't get a chance to hit, because I don't want to mess up that 1-for-1 and that 1.000 average in my career."
Peralta, 34, originally signed as an infielder, but he doesn't claim to be a good hitter.
"I think that was a lucky shot," he said. "Some guys said I closed my eyes."