[1] Growing up, Merrill was a fan of the Boston Red Sox of Major League Baseball (MLB).

[2] Merrill's junior season at Severna Park was canceled due to COVID-19, after which he focused on physical training and gained over 30 pounds (14 kg) of muscle.

The San Diego Padres selected Merrill in the first round, with the 27th overall pick, in the 2021 Major League Baseball draft.

Merrill split the 2023 season between the High–A Fort Wayne TinCaps and Double–A San Antonio Missions, playing in 114 total games and batting .277/.326/.444 with 15 home runs, 64 RBI, and 15 stolen bases.

[12] Merrill made his major league debut the following day against the Los Angeles Dodgers in the Seoul Series.