San Francisco @ Washington preview

Last Meeting ( Aug 13, 2013 ) San Francisco 2, Washington 4

The Washington Nationals aim for their fifth straight win on Wednesday against the San Francisco Giants, who have dropped a season-high 14 games under .500 at 52-66. Both teams have reason to be upset after falling short of preseason expectations, and tempers boiled over in the Washington dugout on Tuesday when Gio Gonzalez and Jayson Werth had to be separated during the Nationals’ 4-2 win. Washington remains 8 1/2 games back of Cincinnati in the race for the second National League wild card.

San Francisco has fallen out of contention while going 29-51 since May 14, and even reigning National League MVP Buster Posey has found himself in a rare slump. The All-Star catcher is hitting .167 (11-for-66) with no home runs and two RBIs in his last 20 games. “More than anything he’s been fighting it,” manager Bruce Bochy said. “The swing is fine. But they’ll all have their moments, and as much as you don’t want to see it, they all go through it.”

TV: 7:05 p.m. ET, CSNBA (San Francisco), MASN (Washington)

PITCHING MATCHUP: Giants RH Tim Lincecum (6-11, 4.18 ERA) vs. Nationals RH Jordan Zimmermann (13-6, 3.10)

Lincecum has bounced back from a disappointing first half by recording five quality starts in his last six outings. The 29-year-old tossed eight shutout innings with eight strikeouts against Milwaukee last Thursday. Ian Desmond is 9-for-11 with one home run against Lincecum, who is 1-4 with a 5.68 ERA in eight career starts against the Nationals.

Zimmermann has struggled since the All-Star break, going 1-2 with a 6.75 ERA in his last four starts. He failed to reach the fifth inning for the second time in four starts last Wednesday against the Atlanta Braves, yielding two runs on seven hits over four frames. Manager Davey Johnson said Zimmermann was dealing with tightness in his neck, but the right-hander said his neck was fine.

WALK-OFFS

1. San Francisco has averaged the fewest runs in the major leagues (2.58 per game) since the All-Star break.

2. Giants 2B Marco Scutaro was scratched from Tuesday’s lineup with a stiff back and is listed as day-to-day.

3. Nationals C Wilson Ramos re-injured his left hamstring on Tuesday and could be headed back to the disabled list for the third time this season.

PREDICTION: Nationals 4, Giants 3