In the middle of the 1947 season, he was released and subsequently joined the Boston Braves, where he played the 1948 World Series as his final appearance in a major league game.

After he was rejected by the Philadelphia Athletics, Washington Senators and New York Giants, in 1934, he took a $50 loan (equivalent to $1,139 in 2023) from his uncle in order to go to the Cincinnati Reds' tryout held in Beckley, West Virginia.

[1] McCormick's manager at the sandlot team encouraged him to switch positions to first base, citing how there was less competition for the spot compared to the outfield.

His performance at the tryout left a lasting impression on former major league player and renowned scout Bobby Wallace, who signed the 23-year-old.

He began the season in a disappointing fashion before his manager, Johnny Gooch, advised him to modify his batting grip.

The change helped McCormick tremendously, as he led the league with a .381 batting average that season[1] and finished with 211 hits, 49 doubles and 15 home runs.

[3] McCormick made his major league debut for the Reds on September 11, 1934, at the age of 23,[2] entering the game as a pinch-hitter for pitcher Ray Kolp in a 5–2 loss against the Brooklyn Dodgers.

In his first day back with the team, he amassed seven hits in a doubleheader[1] and finished the season with a .325 batting average in 83 at-bats.

[8] His impressive performance during the latter half of the season was recognized as being a key factor in the Reds' drive to win the pennant.

His contributions to the team that year led to him being accepted into the "Jungle Club" of Reds' infielders, who gave him the nickname "Wildcat".

At the conclusion of his 1938 rookie season, McCormick married his wife Vera (née Preedy) on October 8.

[14] After his coaching tenure finished, he continued his affiliation with the Reds as a scout, as well as a broadcaster, announcer and analyst on WLWT-TV from 1958 to 1968,[15] before moving back to his hometown and working as the director of ticket sales for the New York Yankees until his death.