Baseball-Reference has posted data that allow us to discover if that claim is true.
The Yankees opened the 1956 season in Washington. In his first at-bat of the season, Mantle hit a two-out home run against Camilo Pascual to give the Yankees a 1-0 lead. He put the game away with a three-run blast in the sixth inning for an 8-2 lead on the way to a 10-4 win.
In 1956, Mantle hit 10 home runs with the score tied, seven home runs with the Yankees behind by one run and six home runs with the Yankees ahead by only one run.
Twenty-three of his 52 home runs, 44 percent, were hit when they were most meaningful.
bWE is a statistic that calculates a team's win expectancy ...
Read Full Article at Bleacher Report - MLB By Harold Friend