Unfortunately for the Nationals, Lannan wasn't able to overcome shaky mechanics, as he struggled his way to an early exit and an 8-1 loss to the Braves. Lannan lasted just 4 2/3 innings and allowed five earned runs on six hits and four walks, as Washington saw its eight-game winning streak come to an end.
As Lannan's problems maneuvering through the Braves' lineup mounted, Atlanta starter Tommy Hanson cruised after some early trouble. Although the Nationals managed seven hits off of Hanson, they scored just one run and struck out nine times.
"They just beat us," said Nationals interim manager Jim Riggleman. "We didn't play as well as we have recently. [Lannan] didn't have his best stuff today."
Lannan set down the Braves in order in the first, but had issues finding the plate in the second. He walked the first two batters and then surrendered a single to Garret Anderson to load the bases. Matt Diaz followed by grounding into a double play, but a run scored thanks to the walks.
The Braves added two more runs in the third on Martin Prado's double and Chipper Jones' single -- which was bobbled by left fielder Josh Willingham for an error, allowing Prado to score -- and broke the game open in the fifth with three more runs. The fifth-inning outburst ended Lannan's night, making it his shortest outing since he lasted just three innings on Opening Day.
"A couple of big walks early in the game really aided our cause," said Jones. "It's not like John Lannan to fall behind and walk many guys. Tonight, he had a couple of lapses, and we took advantage."
"This is just one of those days you have to move past," Lannan said. "It's frustrating, but it's going to happen. I had trouble throwing strikes."
Lannan said his issues were mechanical, and they began in his pregame bullpen session. While Lannan had trouble explaining what the issues were, catcher Wil Nieves saw several glitches in the southpaw's delivery that could have caused problems.
"He didn't have too much control in the bullpen," Nieves said. "He was trying to battle, but his mechanics were all messed up. It looked like he was getting too long in the front [striding too far] and flying open. He wasn't getting on top of the ball like he usually does. He was getting under it, which makes his sinker not work."
Washington's only run of the night came in the first, when leadoff man Nyjer Morgan scored on Ryan Zimmerman's RBI single. Morgan singled to lead off the game and stole second to set up the hit.
The Nationals seemed intent to run on Hanson and Braves catcher Brian McCann, as they finished the night with four steals in five attempts. They might have been a perfect 5-for-5 in stolen bases, had Morgan not been thrown out at third on a call that can only be described as questionable.
Television replays showed that Morgan beat Jones' tag, but third-base umpire Larry Vanover called him out for the second out of the inning. After a brief argument by Riggleman, hitting coach Rick Eckstein was ejected for continuing to argue from the dugout.
The call took some momentum out of a promising inning, and the Braves came back to take the lead in the bottom half.
"If he was safe, we might have got a run out of that," Riggleman said. "Who knows what would have happened with [Cristian] Guzman's at-bat. Maybe they pitch him a little different. But I think we could have gotten a run out of that. But really, the turning point was when they were patient and took some walks the next time up."
It's easy to look at the third inning as a missed opportunity for the Nationals' offense, but Hanson settled in to baffle Washington hitters for the rest of the night. The big righty notched nine strikeouts, including three of Adam Dunn, who finished the night with four.
With the eight-game winning streak behind them, the Nationals have to rebound on Wednesday to avoid the two-game sweep against Braves starter Derek Lowe.
"We've been playing good baseball," Lannan said. "I really didn't help with that, but we'll just have to start another streak [on Wednesday]."
Adam Rosenberg is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.