Surrounded by droves of appropriate imagery, Jack Leiter continued his season-long hunt for the metaphorical buried treasure that could best unlock his abilities on the mound. “It’s kind of just the elusive strikeout pitch,” the Texas Rangers’ rookie right-handed pitcher said Sunday. On Sunday, in an 8-3 series finale loss to the Pittsburgh Pirates at PNC Park, Leiter continued a worrisome trend and swung too far in either direction in leverage counts and failed to capitalize on advantages that he’d built early in at bats. The 25-year-old right-hander allowed three runs on five hits, two walks and two strikeouts but lasted just four innings after his pitch count climbed too high on a hot Western Pennsylvania day.