The strike has not tamed major league baseball's expansion plans. Owners today officially added two new teams -- the Tampa Bay Devil Rays and the Arizona Diamondbacks -- to take the field in 1998. Fans will be permitted to vote on the name for the Tampa team, with the option of switching to the Manta Rays. Meanwhile, federal mediator W.J. Usery is trying to get owners focused on the labor dispute as opening day (April 2) approaches. Today he urged them to make their "best offer" to players next week in an effort to solve the seven-month dispute, which he described as "embarrassing and ridiculous." The National Labor Relations Board, originally slated to rule today on a complaint filed by the players, is pushing that announcement back to tomorrow or next week.