At 6-foot-1 and 250 pounds, the burly DH does not run so much as he chugs.
But with the game tied with two out in the eighth on Sunday, Butler hustled to first base to keep the inning alive.
Then he hurried with all his might a few minutes later and was safe at third, allowing Eric Hosmer to cross the plate with the tiebreaking run in what turned into a 6-4 victory over Washington that snapped KC's seven-game losing streak.
"All you can do is put the ball in play and dig. And that's what I did," Butler said with a grin.
With two out and Hosmer on first and the game tied 4-all, Butler hit a hard grounder that first baseman Adam LaRoche knocked down.
The ball rolled several feet to his right and when pitcher Craig Stammen was late to cover the bag, the slow-running Butler pulled into first with an infield single.
"The pitcher's supposed to get over there," Butler said. "They had to know I don't run very well. But all I could do was run, and I beat him after he didn't get off to a good start at first."
He bobbled the ball momentarily and his throw to third was late, allowing Hosmer to cross the plate on an infield single and making it possible for Royals manager Ned Yost to take a deep breath.
"It seems like when you're going through those (losing) streaks, every decision you make doesn't work," Yost said.
"Do I pinch run? (for Butler) Do I not pinch run? My heart kind of sunk there for a minute thinking as soon as it was hit and I see him going to third. But he ends up making it."
David Lough's RBI single brought in the sixth run as the Nationals saw the end of a five-game road winning streak.
Nationals manager Davey Johnson thought Butler should have been out at first, sending the teams into the ninth tied 4-4.
"(LaRoche) bobbled the ball and then still had time to walk to first," Johnson said. "We should have got him out. With a ball hit right at him you can usually go to first."
Kelvin Herrera (5-6) pitched 1 1/3 innings of relief for only the Royals' third victory in 13 games. Stammen (7-6) took the loss and was part of a shaky defense.
Greg Holland pitched the ninth for his 35th save in 37 opportunities, giving up two singles but striking out the side. Stammen went one inning, gave up three hits and two earned runs.
Butler was not about to say the Royals were due a few good breaks.
"This game never owes you anything. You can't be looking for breaks," he said. "You can just play the game hard and hope the ball falls on your side."
Santana had a 4-1 lead and two out in the seventh when Denard Span's third hit of the day went for his third home run of the year.
Ryan Zimmerman followed with a single, bringing a visit to the mound by Royals pitching coach Dave Eiland. Harper then hit Santana's next pitch over the fence in left-center, bringing Herrera in from the bullpen.
Washington starter Dan Haren entered the game 4-0 in six career starts in Kauffman Stadium and had never allowed more than two earned runs in K.C.
But that quickly changed.
On Haren's third pitch, Alex Gordon hit the 11th leadoff home run of his career. After Emilio Bonifacio walked, Hosmer hit an RBI single. Hosmer was out trying to steal, then Moustakas singled and Perez homered for a 4-0 lead against Haren, who had been 4-2 since coming back from the DL on July 8.
Haren was in danger again in the second and was saved by a standout double play started by LaRoche, who dove to his right to grab a line drive off Gordon's bat. From his knees, LaRoche threw to second base to double off Alcides Escobar.
After that, Haren allowed only two singles while going seven innings. He was charged with four runs and eight hits.
In the Nationals fourth, Desmond homered for the second time in two games. The ball bounced off the facade of the Royals hall of fame behind left field and was estimated at 431 feet.
Span drilled a ball off Santana's right hip with one out in the third, the ball bounding all the way into foul territory behind third base while Anthony Rendon went from second to third.
But after testing the leg and visiting with the Royals trainer on the mound, Santana stayed in to strike out Zimmerman and retire Harper on a shallow fly.
Santana was charged with four runs and 11 hits in 6 2/3 innings, with seven strikeouts and no walks.
Jayson Werth was back in the Nationals lineup at DH after sitting out one game with an infection in his right foot. ... Royals had a fifth straight losing season in interleague competition. ... The Royals face Tampa Bay on Monday to make up a game that was snowed out in May. ... The Nationals finished a 10-game trip to Chicago, Atlanta and Kansas City 6-4.