Thomas Boswell: The Nats" defense does not rest in opening sweep of Marlins Defense hides in plain sight. Baseball's prettiest, trickiest but most dependable element is also its most mysterious. Everybody wants it, but nobody knows exactly what it's worth in runs, wins or dollars or how much to sacrifice to add more of it. But the Nationals are about to get an education. The Nationals traded away a slugger, Michael Morse, who has already hit nine homers in spring training and four more in just three games of the regular season, both totals that lead MLB. Morse was a poor left fielder, perhaps an adequate first baseman and a fine slugger. The Nats went in the diametrically opposite direction, keeping gold-glover Adam LaRoche at first base, adding a swift center fielder in Denard Span and moving a decent center fielder, Bryce Harper, to left field, where he should excel. It's like a controlled lab experiment. Now, we get to see how it works out. The Washington Post's Mike Wise offers his extra points about Bryce Harper and his future professional baseball career. The Miami Marlins think it's working entirely too well. They know they're bad. But they probably didn't expect to come to Washington for three games, lose them all and score only one run on the entire trip. In the first inning on opening day, Ryan Zimmerman saved a run with a diving stop and throw from third base that LaRoche dug out at first base. After that, the leather never stopped slapping the poor Fish in the gills every time they tried to compete. On the last out of the Nats" third straight win, Harper made a running over-the-shoulder catch. During the sweep, Jayson Werth turned a triple into a double and a double into a single on hits down the right-field line. Span ran precise routes in center to make cruising catches in the gaps. Danny Espinosa and Ian Desmond turned double plays. Jordan Zimmermann made two quick off-the-mound fielding gems, including a force at third base in his 6-1 win on Thursday afternoon. And Kurt Suzuki threw out Juan Pierre stealing. In three games, the Nats had one misplay but perhaps eight defensive plays worthy of a star, including a double-rundown double play that went into the scorebooks 7-2-3-4-2. Seldom seen. "Executed perfectly," said Manager Davey Johnson. As a pitcher, you've got an unbelievable infield behind you - all four are gold-glove caliber. You've got speed all over the outfield. Dare the batter to put it in play," said Zimmermann, who struck out just one. Nats GM Mike Rizzo always planned for the team he sees now. "Twenty-seven outs - and no more - that's our goal," he said. You can't afford to give good teams extra outs or they'll kill you. We want pitching, defense, athleticism and speed wherever we can get it. "Michael [Morse] is in the perfect league for him," added Rizzo. We're more of a National League type club - a layered [left-right] lineup, more on-base percentage. And there's a dramatic difference in our outfield. We took a pretty good center fielder and put him in left. Because Span takes perfect routes to the balls in the gaps, our corner outfielders can shade a little more toward the corners, even get to more balls in foul territory.