Opposite dugout: Nationals send Roark to hill for final '14 edition of Battle of the Beltways

Manager: Matt Williams, first year Record: 60-49 Last 10 games: 5-5 Who to watch: 3B Anthony Rendon (.280/.338/.470, 29 doubles, 14 HR, 62 RBIs, 78 R); RF Jayson Werth (.278/.365/.433, 26 doubles, 12 HR, 61 RBIs, 62 R); SS Ian Desmond (.249/.301/.425, 18 doubles, 17 HR, 66 RBIs); RHP Tanner Roark (11-6, 2.74 ERA, 1.08 WHIP) Season series vs. O's: 1-2, 11 runs scored, 14 runs allowed Pitching probable Aug. 4: Tanner Roark vs. Kevin Gausman, 7 p.m., MASN2 HD Series breakdown Instead of resting for their final mutual off-day of the season, the Nationals and Orioles provide one last celebration of regional baseball by meeting at Nats Park for the makeup of a July 8 rainout. The Orioles will be looking to take the season series for the third straight year while the Nats are targeting a split for the first time since 2011. The Nationals own one of the best pitching staffs in baseball, tying for the National League lead and ranking second in the majors with a 3.10 ERA. And they'll be sending out one of their top starters, Tanner Roark, against O's rookie Kevin Gausman in an exciting match-up between young right-handers. Roark leads the Nats rotation with 11 wins and ranks second with a 2.74 ERA, the 10th-best mark in the NL. The 27-year-old has been at his best lately, putting together a tremendous July. He lasted exactly seven innings in all five starts last month and allowed just one run in each of his last four. He's 4-0 with four earned runs in 28 innings over his last four starts for a 1.29 ERA. Gausman has been good as well, going 5-3 with a 3.70 ERA in 10 starts. He has been especially strong his last two starts, allowing four runs in 13 2/3 innings (2.63 ERA) since allowing five runs in four frames on July 20. The Nats back up Roark with one of the best groups of relievers in baseball, ranking third in the NL and fifth in the majors with a 2.89 bullpen ERA. Offensively, the Nats have been solid as well. They rank fifth in the NL with 458 runs, sixth with a .697 OPS, eighth with a .249 average and 11th with 87 homers. But before scoring 11 runs on Saturday, the Nats' bats had gone a little cold. They scored more than four times just once in their previous nine games, averaging just three per contest while being blanked twice during that stretch. Losing third baseman Ryan Zimmerman to a Grade 3 hamstring strain had proven to be quite a problem for the Washington lineup, as the club went 3-6 in its first nine games without him. The Nats have since rebounded a little with two straight wins over the Phillies. Anthony Rendon, who has again moved from second to third in Zimmerman's place, leads the Nats' offense with an .807 OPS. He also has 29 doubles, 14 homers, 62 RBIs, 78 runs scored and 11 steals. Talk about well-rounded. Right fielder Jayson Werth, a former Orioles first-round pick, is having another strong season, posting a .798 OPS to go with 38 extra-base hits, 61 RBIs and 62 runs scored. Shortstop Ian Desmond leads the team with 17 homers and 66 RBIs despite batting .249. Center fielder Denard Span has sparked the Nats from the leadoff spot, batting .422/.500/.438 with five RBIs and 13 runs scored in his last 16 games. That has raised his season slash line to .291/.349/.393. Since these regional rivals last played, the Nats also acquired infielder Asdrubal Cabrera from the Indians to make up for the loss of Zimmerman. So the Nationals are in first place for a reason, and it isn't only their exceptional pitching staff. Both teams will be hoping to increase their division lead by a half-game with their closest challengers getting the day off. With a win, the Nats can up their NL East lead over the Braves to four games while the Orioles can do the exact same, extending their American League East lead to four games over the Blue Jays.