The Washington Nationals' game Sunday against the Cincinnati Reds was fairly well decided by the time Denard Span left it in the eighth inning. If it were closer, Nationals manager Matt Williams said, Span would not have left at all. But the center fielder has been dealing with pain in the patella tendon of his right knee since a quirky play against the Chicago Cubs last week on which he lost his footing before recovering to make a tough catch in the Wrigley wind. As Span chased a line drive by Zack Cozart in the sixth inning Sunday, he felt the pain again. “It’s been kind of off and on since [Chicago],” Span said. “It’s been bothering me. Certain movements — sprinting, trying to decelerate, coming down on it.” Span said the trainers have examined the knee, and that they found “no structural damage.” His prognosis as of Sunday afternoon, then, is to deal with the lingering soreness as best he can.