WASHINGTON -- The deciding factor in the Cardinals' four-game series against the Nationals was defense, with each of the games tilting toward the club that played cleaner in the field.
Though there would be no adding to the seven unearned runs already scored in an early-season matchup between projected postseason contenders, it was a pair of plays not made that kept St. Louis from reeling off its fourth consecutive series victory.
This time the bullpen couldn't provide the bailout, and with two runs off Carlos Martinez in the seventh and a walk-off sacrifice fly against Seth Maness, the Nationals salvaged the series split with a 3-2 win Sunday. Denard Span's game-winning RBI capped the three unanswered runs scored by Washington.
"We talk so much about the pride we're taking in trying to be that clean defensive team, which I still know that we are," manager Mike Matheny said. "But I think it's just showing the caliber of competition. When you give extra outs to a good offense, it's going to come back to bite you."
The Cardinals were generous with the extra outs in front of a Nationals Park crowd of 27,653. Their pitchers issued six walks -- five by Shelby Miller -- and Matt Carpenter's sixth-inning error was the team's seventh in seven games on this road trip.
More costly than those, though, were two other plays not made. It was certainly not a stellar showing for a Cardinals team retooled this offseason with the focus of improving defensively.
The Nationals pulled to within one on an Ian Desmond single that skipped off the glove of second baseman Daniel Descalso in the seventh. The tying run scored on a single that followed.
"I just misread the hop there," said Descalso, who had come in as part of a double switch in that inning. "I should have taken the extra step to get in front of it, play it safe and get an out."
Washington then sparked the game-winning rally with Danny Espinosa's sharp line drive though third baseman Carpenter's legs with one out.
"That's a play I'm expected to make, and that's a play I expect myself to make," Carpenter said. "I didn't make it, and it ended up costing us."
Espinosa moved to third on Jose Lobaton's single and, after pinch-hitter Nate McLouth walked, Span answered the Cardinals' five-man infield by lifting a fly ball to right fielder Jon Jay, who had shifted to left when Matheny pulled his left fielder, Allen Craig, in as an extra infielder.
Espinosa scored easily.
"Those aren't easy at-bats," Espinosa said. "You really have to make those guys come to you. They make good pitches and they throw hard. … Everyone did a good job of making them come to them and getting a good pitch."
The run further inflated Maness' ERA (now 7.11), though his fielders haven't helped him either of his last two times out. On Wednesday, a line drive not caught by Jhonny Peralta spiraled into a three-run inning. Peralta was not charged with an error.
"He's had a couple of them that cost him quite a few runs that didn't seem to look right and our guys defensively believe they are plays that can be made," Matheny said. "He's thrown better than what his ERA is showing at least."
Sunday's starting matchup was a marquee one between Stephen Strasburg and Miller, both first-round Draft picks in 2009. In many ways, Strasburg's outing was smoother, but it was Miller who left with the lead.
Miller had command troubles and issued four of those five walks before he allowed his first hit -- a two-out single by Espinosa in the fourth. Miller walked three in a four-batter span in the third but struck out Adam LaRoche to end the threat.
He suggested afterward that he felt a tight strike zone cost him some possible strikes in that 32-pitch inning.
"But at the end of the day," Miller said, "you have to throw to the zone."
Miller did notch seven strikeouts, an indication that he at least found a way to get his command back at times. For all the early attention paid to the five home runs he allowed in his fist three starts, Miller has had even more problems limiting the walks. He's issued 14 in 22 2/3 innings, some of the problems due to getting mechanically out-of-whack.
"Something there is triggering him to fall off to the side too much [as he finishes], which gets the ball out of the zone," Matheny said. "Sometimes a tough adjustment to make midgame."
Miller stranded eight runners through the first five innings, and got help from Randy Choate to hold a 2-0 lead through the sixth. After inheriting two runners and having another added on an error by Carpenter, Choate closed the inning with a force out and groundout.
The rest of the Cardinals' bullpen couldn't follow suit. Martinez coughed the lead up in the seventh as the Nationals strung together four consecutive singles, the second to last of which Descalso couldn't glove.
"That's usually how it goes," Descalso said. "If you make a few defensive mistakes, it costs you."
The Cardinals maximized the five hits off Strasburg, who struck out nine in six innings. Matt Adams doubled to open the second, moved to third as Yadier Molina extended his hitting streak to 11 games and scored on a double play. Miller's RBI double, which followed Peter Bourjos' third walk of the season, padded the lead.
Both the double and RBI were the third in Miller's career. He was the third Cardinals' starter in this series to help his own cause by driving in a run.
"I was pretty happy we were able to put a couple together," Matheny said. "Then when we get to the later innings, we have a lot of faith that our 'pen can come in and shut the door. But they're not going to be able to do it every single night."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.