Washington is 1-7; in the franchise's two-city history, only this edition and the 1998 Montreal Expos opened 0-7, according to STATS LLC. Martis (1-0) gave up two runs and five hits in by the far the most effective performance by any member of Washington's young starting rotation in 2009. Mike Hinckley, Joe Beimel and Joel Hanrahan followed with 2 2-3 innings of perfect relief.
Dunn hit a three-run shot off Joe Blanton (0-1) in the first inning, while Josh Willingham hit his first homer with the Nationals as a pinch-hitter in the seventh off Chad Durbin. Elijah Dukes and Alberto Gonzalez connected against Jack Taschner during Washington's four-run eighth to put the game out of reach.
Offense, though, has not been a problem this season for the Nationals, who have averaged 4.9 runs. Pitching, well, that's another matter. Martis lasted three innings in his rain-interrupted season debut last week - long enough to allow three runs - and Nationals starters were a combined 0-5 with a 10.73 ERA entering Thursday.
"That's the thing - it hasn't been one or two guys, but it's been the four guys who so far haven't been able to give us the quality start that we've been looking for," manager Manny Acta said before the game. "That's what makes it a little bit more of a big of a deal."
Neither of the clubs at Nationals Park on Thursday has pitched well: They came in with the NL's two highest ERAs, Washington at 7.71 and Philadelphia at 6.68. Opponents were batting .321 against Washington's pitchers - more than 50 points higher than the league average.
Still, Martis was nearly matched by Blanton, who certainly permitted plenty of hits (eight) but only one that produced any runs during his six innings: Dunn's drive to right, his third homer with the Nationals.
The Phillies got to Martis on Raul Ibanez's RBI single in the fourth and Jimmy Rollins' sacrifice fly the next inning, making it 3-2. But Philadelphia's bullpen turned the game into a blowout.
Notes: The Phillies wore black patches with the initials "HK" on their uniforms in memory of longtime broadcaster Harry Kalas, who died after collapsing at the stadium before Monday's game. A video tribute to Kalas was shown on the scoreboard before Thursday's first pitch. ...
The last big league team to start a season with at least eight losses was the 2003 Detroit Tigers, who began 0-9, according to STATS LLC. ... Washington 1B Nick Johnson, moved up to No. 2 in the batting order, had three hits. ... Because of days off, the Nationals began the season with a four-man rotation; rookie Jordan Zimmermann is scheduled to be brought up from the minors for his first major league start Monday against Atlanta. ...
Nationals SS Cristian Guzman, who hurt a hamstring running to first base Monday, was out of the lineup, but was available to pinch hit. ... As part of "Military Opening Night," the Nationals wore blue uniforms with a stars-and-stripes design in the "DC" on their jerseys and hats.