"As ballplayers, we've played in heat all our lives," Johnson said. "But it was pretty intense out there today."
Strasburg exited before the fourth inning, marking the shortest outing of his season (his previous low was four innings) and the briefest of his career since Sept. 11, 2011, against Houston. He scattered just two hits, but allowed three runs (all earned) while walking four.
First pitches at the start of his last two outings -- the last also coming a mile above sea level in Denver -- have been in the triple-digits, and the San Diego native said he did all he could leading up to the game to prepare himself.
"It's tough out there," Strasburg said. "Obviously, I wanted to go out there and compete. I expected a lot more out of myself. By no means was I going out there thinking I wasn't prepared for it. I did everything I could to be ready for it, as far as hydrating. You've just got to learn from it. It's a tough situation."
Johnson said he was prepared to see how warmups in the fourth inning went, but after hearing reports of Strasburg looking dizzy, and seeing the player up close, he made a call to the bullpen.
Strasburg, who had three IVs of saline solution administered in the clubhouse afterward, said he had made every effort to come down into the cooler tunnel outside the dugout between innings to beat the heat.
"In the bullpen, he looked fine to me," catcher Jesus Flores said. "But as the game started, he kind of started to physically show some weakness. He couldn't command his pitches at all today. He was leaving the ball up in the zone."
The Braves did their damage off Strasburg in the third, when he walked two hitters before Jason Heyward laced a double over left fielder Tyler Moore's head. Freddie Freeman plated Martin Prado with a sac fly, and Heyward later scored on a Dan Uggla double. Strasburg was relieved before the fourth by scuffling right-hander Chien-Ming Wang, who gave up hits to three of the first four hitters he faced as Atlanta went up 6-2.
"He's just not right," Johnson said of Wang. "His release is not right, and we're concerned about it. He's a veteran pitcher. ... We're in the heat of battle. So I don't know."
Wang, in his second season with the Nationals, worked as a starter all last year but has since been demoted to the bullpen. His performance hasn't improved, and he now carries a 7.61 ERA on the year.
"My arm feels pretty good and I think my arm slot, I got back a little bit," Wang said through translator John Hsu. "It was just unfortunate I didn't get the ball to locate well today."
Trailing, 7-2, after the fifth, the Nationals staged a bit of a comeback in the sixth and seventh before falling short. Moore and Flores logged RBI singles, and Adam LaRoche doubled home a run.
But the Nats went down in order in the eighth, and Craig Kimbrel earned his 23rd save of the season after pitching a perfect ninth.