PHILADELPHIA — When Kyle Schwarber heads to the batting cage in the underbelly of Citizens Bank Park, his routine looks the same most days: tee work, flips, a gradual progression to harder concepts as Phillies assistant hitting coach Rafael Pena throws to him.He has tweaked some of his work lately to focus on righties, against whom he has a .613 OPS in July. Perhaps it’s why Schwarber went 4-for-10 with two walks while seeing two right-handed starters against the New York Yankees this weekend.“It’s just what Kyle does,” hitting coach Kevin Long said. “He grinds, and he finds a way to figure it out.”Maybe his pair of walks, single and sacrifice fly weren’t the flashiest plate appearances in Sunday’s game. The Phillies had five extra-base hits and went 6-for-15 with runners in scoring position, breaking a four-game losing streak with an 11-4 win.How many players will the Mets trade by the deadline?Ken Rosenthal and Johnny SweetSchwarber’s success demonstrated a fundamental, obvious truth: So much is easier for the Phillies when Schwarber, Bryce Harper and Brandon Marsh reach base. Schwarber scored twice Sunday while Harper and Marsh added a run apiece, triggering a catharsis through a Citizens Bank Park that had grown agitated (and filled with opposing fans) throughout the week.Yet Marsh, Harper and Schwarber have been at the center of the Phillies’ post-All-Star break slide. Harper entered Sunday hitting .147/.272/.265 with a .536 OPS in July, and Marsh’s slash line reads .152/.222/.242 with a .465 OPS — a stretch that has seen him platooned again. Schwarber has been markedly better, but his numbers still feel human for the NL leader in home runs (.246/.349/.403).Since the start of July, the Phillies rank among the worst teams in baseball in OBP (.294; 25th) and OPS (.671; 25th). They are 3-6 since the All-Star break, slipping to 5 1/2 games behind the Atlanta Braves in the NL East. They scored one or zero runs in five games of their nine-game, post-All-Star homestand.Whatever happens from here, this club cannot get where it wants to go without better at-bats from Marsh, Schwarber and Harper. Even when others contribute, as Alec Bohm and Bryson Stott did Sunday, or pick up slack atop the lineup as Trea Turner has, everything is better when those three reach base. Whom would Bohm have had to drive in if not for Marsh, Harper and Schwarber on the bases in the third inning?