Masi was one of the National League‘s top defensive receivers, and uncommonly fast for a catcher. A weak bat held him back initially, but he became a first-stringer due to his fine handling of Braves pitchers, from knuckleballer Jim Tobin to stars Warren Spahn and Johnny Sain.
As a pinch runner in the first game of the 1948 World Series, Masi was safe on a controversial call on a pickoff attempt by Cleveland pitcher Bob Feller and shortstop Lou Boudreau. He subsequently scored the game’s only run. In 1949, during his 11th season with the Braves, he was traded to the Pirates, who sold him to the White Sox that winter. In his first season in the AL, he led the league’s catchers in fielding.