The New York Mets and their billionaire owner Steve Cohen have a new top lawyer in Kasowitz LLP partner Kenneth David, a veteran litigator who will join the Major League Baseball club as of Dec. 1, according to a team statement.

David’s move to the Mets comes at a time when many professional sports teams—such as the team’s National League rivals Atlanta Braves and San Francisco Giants—have sought to make their home fields the hub of larger mixed-use real estate developments.

Cohen is closing in on an $8 billion deal to build a casino complex next to the ball club’s …