He did not play a minor league game in 2020 due to the cancellation of the minor league season caused by the COVID-19 pandemic.[7] McCarthy started 2021 with the Amarillo Sod Poodles before being promoted to the Reno Aces.[8] Between the two teams he batted .253/.332/.500 with 29 steals in 33 attempts.[9]
The Diamondbacks promoted McCarthy to the major leagues on August 27, 2021.[10] On August 29, McCarthy collected his first career hit, an RBI double off of Philadelphia Phillies starter Ranger Suárez.[11] McCarthy finished the 2021 major league season with a .220/.333/.373 slash line, with 13 hits, 3 doubles, 2 home runs, 4 RBI, and 8 walks, all in 24 games.[12]
In 2022 he batted .283/.342/.427 in 321 at bats, with 23 stolen bases in 26 attempts.[13] He had the fastest sprint speed of all major league right fielders, at 30.1 feet/second.[14]