Possible Clues:

• He said 'I didn't really say everything I said'
• "I really didn't say everything I said" sayer
• 'You should always go to other people's funerals; otherwise, they won't come to yours' sayer
• Yogi in the New Jersey Hall of Fame
• Immortal catcher with '-ism' associated with his first name
• Who once said 'You wouldn't have won if we'd beaten you'
• 'I didn't really say everything I said' speaker
• 'If you can't imitate him, don't copy him' speaker
• Source of Yogi-isms
• Malapropist Yogi