The Washington Nationals possess nearly all the strengths a baseball team can, and they put many on display Saturday afternoon. They can overcome the worst start of Jordan Zimmermann’s splendid career with a powerful offense. They can unleash a 19-year-old cyclone on the base paths. They can bring power arms from their bullpen. But in the intensity of a pennant race, the smallest weakness may turn crucial at the worst moment.

After the Nationals and St. Louis Cardinals traded blows for an entire loopy Saturday afternoon, after dusk encroached and 34,004 had clapped and shrieked for nearly four hours, the Nationals’ clearest flaw led to their 10-9 loss: For the life of them, they cannot prevent runners from stealing bases.

Drew Storen took the loss, not so much for his pitches but for the pace at which he delivered them. In the ninth inning, with the score tied thanks to his own escape in the eighth, Storen allowed Allen Craig a leadoff single. With one out, Craig bolted for second base. He had such an overwhelming jump, catcher Jesus Flores did not bother throwing the ball. David Freese immediately singled Craig home, the winning run scoring following the pivotal steal.

The steal off Storen sealed the game, but too much had happened to fully blame any one player or moment. Zimmermann wanted his share. As the Nationals scored at least eight runs for the fourth straight game, Zimmermann allowed a career-high eight earned runs in 32 / 3 innings, the first time he could not escape the fourth inning since September 2010, in his first two major league starts after Tommy John surgery. “This loss is totally my fault,” Zimmermann said.

The Nationals could at least take solace in another Atlanta Braves loss, which kept Washington’sdivision lead at 6½ games and dropped its magic number to 24. “The important thing is, we took a game off the calendar,” said Jayson Werth, who left in the ninth with cramping in his hamstring. “Nothing changes.”

Both Adam LaRoche and Danny Espinosa clobbered home runs. The Nationals took a 6-2 lead after two innings that was erased by Zimmermann’s eight hits allowed, including two homers. Bryce Harper’s bold dash home in the sixth would give the Nationals a 9-8 lead, and Sean Burnett’s leadoff walk in the eighth led to another tying run for the Cardinals.

The wild action led to the ninth and to Craig’s steal. “He just timed me,” Storen said. “That’s just where it is. I’m just concentrating on trying to get a groundball there. And he just took the base.”

The official scorer ruled defensive indifference, a decision that would rightfully be reversed for a stolen base. In the ninth inning of a tie game, the Cardinals had not accepted a favor. They had exploited a flaw. The Nationals have allowed 97 stolen bases in 113 attempts this season, and opponents have noticed. Craig, a thick-bodied slugger coming off knee surgery, had one steal this season.

“Once they see it, they’re going to take a shot at it,” Nationals bench coach Randy Knorr said.

All in the clubhouse agree that slow deliveries by pitchers, especially relievers, are to blame for the season-long trend. The quickest Nationals relievers take about 1.5 or 1.6 seconds to deliver the ball. Storen has pitched at 1.8 this year, and on Saturday some pitches took him two seconds. Those times make it essentially impossible for the catcher.

“You can throw over [to first base] as much as you want,” Knorr said. “But if they’re slow getting their leg up and getting it to the plate, it doesn’t matter.”

The steal would have been moot if the Cardinals had not exploded against Zimmermann. Last year, the Nationals limited Zimmermann’s innings in the same fashion they will restrict Stephen Strasburg this season. The reins are off this season. When he stepped on the rubber Saturday, Zimmermann had thrown 161 innings, his same total as last year.

Despite a midseason inflammation flare-up in his right shoulder, the Nationals have not been concerned. Still, Zimmermann’s performance has flagged. On July 28, he had a 2.28 ERA and had thrown at least six innings in all 21 of his starts. In his last six starts, he has reached six innings once and punched up a 6.23 ERA.

The problem, Zimmermann said, is not his shoulder. “I feel great,” he said. “I feel strong.” Instead, he has been opening his front shoulder too early in his delivery, causing pitches that would have been on the corner to fly over the middle.

“When it was going good, I felt like I could go out there and throw anything and it would be a strike or a groundball,” Zimmermann said. “I’m trying to do the same thing I’ve been doing all year, and they’re just putting the ball in play and hitting the ball harder.”

The Nationals’ bats briefly went silent, but in the sixth they bailed out Zimmermann. Espinosa led off with a homer. With two outs, Werth slammed a double off the right field wall and Harper followed with a walk. Ryan Zimmerman slashed a single to right field.

Werth sprinted home with the tying run, drawing a throw from Craig in right field. As the throw came through to catcher Yadier Molina, Harper rocketed to third. A former catcher, he expected Molina would throw to second as Zimmerman scooted toward second. “I would have done the same exact thing if I was catching,” Harper said. “I was just thinking to myself, ‘What would I do?’ ”

Molina fired to catch Zimmerman in no-man’s land. Harper never broke stride. He barreled feet-first into home, under Molina, as the ball pinballed back. The Nationals had taken a 9-8 lead.

They would not hold it. So much led to the decisive steal. “It always sucks, because at the end it happens and you go, ‘That’s why you lost the game,’ ” Knorr said. “That’s not why we lost.” But it certainly added to the loss, and the Nationals can only hope the weakness will not obscure their strengths again, when it may matter even more.