The departing chairwoman of the National Labor Relations Board won praise from the nation’s biggest labor group Saturday as she leaves a panel that’s facing key vacancies and an uncertain future. NLRB Chairwoman Wilma B. Liebman’s leaves the board after her term ends at midnight Saturday. She has served on the body for nearly 14 years after an initial appointment under President Bill Clinton. The White House has designated NLRB member Mark Gaston Pearce to replace Liebman as chairman. In addition to Liebman’s tenure ending, NLRB member Craig Becker’s term expires at the end of the year. Without new people...