He was known for his gravelly voice and dramatic style, a "whiskey tenor" as sports announcer and executive David J. Halberstam has called it.
As Halberstam's book Sports on New York Radio notes, McCarthy is considered one of horse racing's great callers, setting the stage for well-known voices from Cawood Ledford to Dave Johnson. He was the first public-address announcer at a major American racetrack, Arlington Park in Arlington Heights, Illinois.
In addition to being a race caller for racetracks and NBC Radio, he was a top boxing announcer, too. His most often replayed boxing sportscast is probably his NBC radio call of the 1938 Joe Louis-Max Schmeling rematch at Yankee Stadium:
Later that same year he called the famous Seabiscuit / War Admiral match race, including this phrase in the final stretch run, as Seabiscuit shocked the horse racing world by outrunning the heavily-favored War Admiral:
McCarthy is also known for having mis-called the 1947 Preakness Stakes when a crowd standing on a platform blocked his view of the far turn, just as two horses with similar silks switched places. (Chic Anderson, one of McCarthy's most famous descendants as a track announcer, made a similar mistake in the 1975 Kentucky Derby.) As with Anderson later, McCarthy's quick and humble admission of the mistake helped the criticism eventually blow over.