WASHINGTON — A funny thing happened on the way to Ryan Helsley’s usual forum.The St. Louis Cardinals were dutifully trotting along through another one of their games that sets up for the kind of ninth inning that has made Helsley an All-Star. During his 6 1/3 superb innings, starter Miles Mikolas never pitched with more than a two-run lead. He was relieved by Andrew Kittredge in the seventh inning because once again the Cardinals had a tight, tense game that seemed destined like so many others to be decided by three or fewer runs.And then came the eighth. Along came the ninth. Alec Burleson added three RBIs in the final two innings as the Cardinals turned a close game into a getaway-day stroll. The Cardinals scored four runs in their final two at-bats and shut out the Washington Nationals, 6-0, on Monday at Nationals Park. The victory, the Cardinals’ fourth on the road trip and 12th in their past 17 games, secured a win in the four-game series in the nation’s capital.The Cardinals have not lost a series since a mid-June visit to Miami.They’ve won six of their past eight series to surface from a 3033 record into contention and their best winning percentage in more than a year, at 48-42.Throwing more sliders than he did any other pitch, Mikolas kept a brisk pace to one of his most expedient starts of the season. He pitched around two singles in the first inning and did not allow another runner to reach third base until the fifth inning. Mikolas (7-7) scattered six hits and did not allow a run or a walk through his 6 1/3 innings. He struck out three. The Cardinals backed Mikolas with home runs from Paul Goldschmidt and Burleson. Burleson’s tworun single in the top of the ninth inning set the final score and sent the Cardinals home for the final stand of the first half and rain that threatens to interrupt it as early as Tuesday.Lefty JoJo Romero collected the final four outs of the game for the Cardinals.Power ball: going soloFirst baseman Goldschmidt and Burleson, who will moonlight some at first base to keep his bat in the lineup, widened the Cardinals lead with solo homers, each to start and inning.Burleson, who leads the Cardinals with nine home runs during the past five weeks, drilled a pitch 406 feet to being the eighth inning.His 14th ...