Possible Clues:

• Giant nicknamed 'Master Melvin'
• Mel of the old Giants
• Outrageous, in Internet slang: Abbr
• Mel the baseball legend
• Legendary Giants slugger Mel
• Polo Grounds great Mel
• Memorable Giant
• Legendary Giant slugger Mel
• First National Leaguer with eight consecutive 100-RBI seasons
• Giants' Hall of Famer Mel