In his first MLB game, on September 15, 1946, he shut out the Cleveland Indians 2–0, allowing seven hits and three bases on balls. In his final start of the year, on September 29 at Shibe Park, McCahan went seven innings against the New York Yankees and allowed only two runs (both earned), but the game was ended prematurely with the Athletics trailing 2–1 by a city curfew that prohibited night baseball on Sundays in Philadelphia.
In his inaugural MLB contest, on September 15, 1946, he shut out the Cleveland Indians 2–0, permitting seven hits and three walks. In his last outing of the year, on September 29 at Shibe Park, McCahan pitched seven innings against the New York Yankees, yielding only two runs (both earned), but the game was terminated prematurely due to a city curfew that prohibited night baseball on Sundays in Philadelphia.