After more than three decades as the top lawyer for Major League Baseball’s San Francisco Giants, longtime legal chief John “Jack” Bair is putting on a different cap—but will remain in the C-suite for the same team.

Bair’s new role as chief development officer for the Giants will see him take the lead on a $1.5 billion real estate project that will include the headquarters of financial services giant Visa Inc.

The Giants are part of a growing trend of professional sports teams to expand their business base, with a 28-acre mixed-use development called Mission Rock evolving across from …