Possible Clues:

• Catcher with a record 10 World Series rings as a player
• Baseball great Yogi
• Only player with 10 World Series championships
• Yogi who said 'You can observe a lot by just watching'
• Yogi who coined the phrase 'It ain't over till it's over'
• Immortal catcher with "-ism" associated with his first name
• Oft-quoted Yankee
• Three-time American League M.V.P. of the 1950s
• Yankee great with his own New Jersey museum
• ''It ain't over. . .'' catching great