Possible Clues:

• MLB team with Mr. and Mrs. mascots
• Shea squad: Abbr.
• NL team
• Big Apple MLB squad
• Citi Field org.
• M.L.B. team with a bridge in its logo
• Queens squad, for short
• 'Miracle' team of '69
• Team that won a world championship in its eighth yr.
• Miracle workers of '69