McNally served in the United States Army Air Corps during World War II.

He never played high school sports, but earned letters in football, baseball, basketball, and track at Saint John's University in Collegeville, Minnesota.

"On the way there", McNally said, "we passed a theater on Hennepin Avenue, and up on the marquee I saw the name of the movie that was playing, Blood and Sand with Rudolph Valentino.

On November 25, 1928, the NFL's Pottsville Maroons played the visiting Green Bay Packers at Minersville Park in a driving snow storm.

[5] After the Maroons folded in 1928, McNally went to the team against which he scored Pottsville's last NFL touchdowns: the Green Bay Packers.

In 1937, McNally moved on to the Pittsburgh Steelers (then called the Pirates), where on his first play he ran back a kick 92 yards for a touchdown.

[7] The Pittsburgh's President Art Rooney hired McNally for the 1937 season to be both a player and a coach for the NFL's Pirates.

In his first season as coach, McNally's team was able to muster only a 4–7 record, which was still good enough for 3rd place in the NFL Eastern conference.

As the story is often told, McNally was instead attending a football game at the Rose Bowl in Los Angeles.

Friends in the press box questioned McNally as to why he was on the West Coast and he replied that the Pirates had an open date.

For the 1940 and 1941 seasons, McNally took over the coaching position with the Kenosha Cardinals, an independent pro team that had formerly played in the American Professional Football Association of 1939.

McNally coached football again at St. John's University (Minnesota) from 1950 to 1952 where he amassed 13–9 record during his three-year stint.

After the war McNally attempted to rejoin the Packers in 1945 but was injured by two tacklers while returning a punt in an exhibition game and retired permanently from professional football.

[15] When the Pro Football Hall of Fame was founded in 1963, McNally was among the 17-member inaugural class, which included Curly Lambeau, Jim Thorpe, Sammy Baugh, and Bronko Nagurski.