It appeared that right-hander Garrett Mock, who started for Washington, wasn't ready to pitch. He has yet to show that he is the type of starter that he was at Triple-A Syracuse. He gave up five runs -- three earned -- in 5 1/3 innings.
The Padres went to work on Mock in the first inning. After Tony Gwynn singled and advanced to second on a wild pitch, Everth Cabrera bunted toward Mock, who made a throwing error, which allowed Cabrera to reach.
Adrian Gonzalez then hit a sacrifice fly to send Gwynn home. Two batters later, Chase Headley doubled down the right-field line to drive in Cabrera.
Mat Latos started for the Padres and allowed a homer to Cristian Guzman in the bottom of the first, but he settled down and lasted 5 2/3 innings to earn his first Major League win.
The Nationals had other chances to score, but they couldn't take advantage. In the third inning, they had runners on first and second and nobody out, but Adam Dunn hit into a double play. After Nick Johnson walked, Josh Willingham grounded out to end the inning.
"He improved on the efficiency," Padres manager Bud Black said of Latos. "He got into some deeper counts, but threw strikes when he needed to."
Washington had a chance to get back in the game off San Diego's bullpen in the eighth inning. It loaded the bases off off reliever Mike Adams, but Guzman struck out to end the threat.
"One thing I told the ballclub was, 'I know how hard it is to hit,'" Riggleman said. "So if we hit, I'm the happiest guy in the world. If we don't hit, I know it's not from lack of effort or lack of intensity. I don't even get upset about not hitting with men on base. I get upset about the other stuff -- not making plays, not getting signs, the details of the game. You have to take care of the details.
"Eventually, if people don't hit enough, then [interim general manager] Mike Rizzo will get someone else in here. You have to hit and pitch. I can't help them with their hitting. I can't help them with the pitching, so I have to make sure they take care of the little things -- the details. We didn't take care of the little things today, and that's what upset me about that ballgame today."
In the fourth inning, San Diego increased its lead when Luis Rodriguez hit a solo home run. In the sixth, Rodriguez delivered again, hitting a two-run single.
In the seventh, Nats reliever Jason Bergmann allowed Gwynn, who led off the inning, to reach base on a throwing error. Three batters later, Kevin Kouzmanoff doubled home Gwynn.
The Nationals scored their last run of the game when Ryan Zimmerman homered in the sixth off Latos, but the damage was already done.
Friday was not the first time Washington has shown a lack of effort. It has been this way for most of the season. Defense, for example, has played a large role in the team having the worst record in baseball. The Nationals have committed 94 errors in 96 games.
"The fans don't deserve to see us play sloppy like that," said catcher Josh Bard, who made an error in the fourth inning. "We played one of our worst games. ... We have to get better."
Asked if Riggleman got his point across after the game, Bard said, "You have to play the game the right way and control what you can control. It's not a quick fix."