Quoted in Sporting News, 7 Aug. 1971. Berra says in The Yogi Book (1998) that he was referring here to the difficulty of playing left field in Yankee Stadium in late autumn when "the shadows would creep up on you and you had a tough time seeing the ball off the bat."
"Global Warming and the Future of Humanity: An Interview With Noam Chomsky and Graciela Chichilnisky". Interview with C.J. Polychroniou, truthout.org. September 17, 2016.