Opposite dugout: Struggling Rockies always dangerous because of potent lineup

Manager: Walt Weiss, second year Record: 40-58 Last 10 games: 3-7 Who to watch: SS Troy Tulowitzki (.340/.432/.603, 18 doubles, 21 HR, 52 RBIs, 71 R); 1B Justin Morneau (.312/.345/.502, 20 doubles, 13 HR, 60 RBIs); RF Charlie Blackmon (.305/.351/.477, 17 doubles, 14 HR, 52 RBIs, 18 SB); LHP Jorge De La Rosa (10-6, 4.39 ERA, 1.30 WHIP) Season series vs. Nats: 0-3, 7 runs scored, 18 runs allowed Pitching probables July 21: Franklin Morales vs. Doug Fister, 8:30 p.m., MASN HD July 22: TBA vs. Jordan Zimmermann, 8:30 p.m., MASN HD July 23: Jorge De La Rosa vs. Stephen Strasburg, 3 p.m., MASN HD Series breakdown The National League's best offense meets the majors' best pitching staff for the second time this month, as the Rockies welcome the Nationals to Denver. Whether winning or losing, the Rockies have swung a potent bat this season, leading the majors with a .778 OPS and a .280 average while leading the NL with 464 runs and 115 homers. The Nats had their way with the Rockies from June 30 to July 2, outscoring them 18-7 during a three-game sweep in D.C. But Colorado has capitalized offensively on perhaps the best home-field advantage in the majors, and now the season series heads west. The Rockies lead the big leagues in runs, homers, average and OPS at home. Their .872 home OPS is 82 points higher than the runner-up and their 286 runs at home are 41 more than the next team. Shortstop Troy Tulowitzki, whose status is in question after leaving Saturday's game with a leg cramp, has continued to be arguably the best hitter in the majors this year. Tulowitzki leads the league with a .340 average, a 1.032 OPS and 71 runs scored. He also has 21 homers and 52 RBIs. First baseman Justin Morneau is having a terrific year with a .312 average, 20 doubles, 13 homers and 60 RBIs. Outfielder Charlie Blackmon has also been a big part of the Rockies lineup by batting .305 with 17 doubles, 14 homers, 52 RBIs and 18 steals. But despite all that, the Rockies have tumbled to the worst record in the NL. Colorado has lost five in a row and seven of 10 to slip to 6-23 since June 16. During that 29-game cold stretch, the Rockies have averaged 3.7 runs per game and they're still 24-25 at Coors Field. But Colorado's pitching has been atrocious. The club has been outscored 180-107 over the last 29 games, surrendering an average of 6.2 runs per game during that time. The Rockies pitching staff has been a polar opposite of the team's offense, rankings-wise, as it has a major league-worst 5.03 team ERA, a league-worst 5.22 rotation ERA and an NL-worst 4.76 bullpen ERA. Colorado has surrendered a major league-high 114 homers. The Nats will face the Rockies' best healthy starter, left-hander Jorge De La Rosa on Wednesday in a solid pitching match-up with Stephen Strasburg. De La Rosa is 10-6 with a 4.39 ERA, but has been even better lately with three straight quality starts. He has allowed four runs in 18 innings for a 2.00 ERA over his last three outings. Left-hander Franklin Morales (5-4, 5.26 ERA) will take on Doug Fister in tonight's series opener while Tuesday's opposition for Jordan Zimmermann has yet to be determined. Recently signed veteran Chris Capuano is considered an option for that start. The Rockies have been struggling, in large part because of their pitching, but their lineup always makes them dangerous. It should be a fun few days seeing the NL's best arms take on the NL's best bats as the Nats look to keep pace atop the NL East.