Baseball players, for the sake of their sanity, strive to minimize the importance of any single outcome. Sometimes circumstances force them to admit victory becomes more consequential, that a win means more to their psyche than in the standings. On Sunday afternoon, “Turn Down For What” blared through a clubhouse that had been don’t-wake-the-baby silent for days, and the Washington Nationals arrived at one of those moments. Doug Fister had lifted the Nationals to a 5-2 victory over the Pittsburgh Pirates at PNC Park, a win that served as a relief valve. They snapped a four-game losing streak that spanned every member of their rotation except Fister. They broke a string of excruciating defeats — they had outscored opponents by two runs over their previous seven games despite losing five of them. They ensured they would hit Memorial Day at .500 and could hope they had taken the first step forward from mediocrity as they return to Nationals Park. They avoided their first four-game sweep since the opening series of Jim Riggleman’s tenure. For all those reasons, the Nationals could break with protocol. Needing to win is a concept foreign to baseball’s six-month grind. And yet Manager Matt Williams said afterward, “We needed this one today.” “Today was an important win,” reliever Craig Stammen said. “We needed to break that losing streak, get a good vibe as we go home — and not with our tail between our legs.” The Nationals acquired Fister during the offseason to augment their starting rotation, not to top it. But when Fister climbed the mound Sunday afternoon — and now that he is healthy — there may be no other starter they prefer. He allowed one run in 51 / 3 innings, yielding six hits while striking out four.