Lacy was selected by the
Kansas City Royals with the fourth overall pick. He signed with the Royals on June 23 for a bonus of $6.67 million. Lacy made his professional debut in 2021 with the
Quad Cities River Bandits of the
High-A Central. Over 14 starts, he went 2-5 with a 5.19 ERA, 79 strikeouts, and 41 walks over 52 innings. He missed over two months due to a shoulder injury. He was selected to play in the
Arizona Fall League for the
Surprise Saguaros after the season. Lacy opened the 2022 season with the
Northwest Arkansas Naturals of the
Double-A Texas League. In 15 combined appearances split between the Naturals and the rookie–level
Arizona Complex League Royals, he accumulated a 10.61 ERA with 35 strikeouts across 28 innings pitched. Lacy did not pitch for the Royals organization in 2023 due to ongoing back issues. On March 19, 2024, Lacy underwent
Tommy John surgery, which caused him to miss the entirety of the 2024 season. On June 27, 2025, Lacy was placed on the full-season injured list ending his season without appearing in a game. On April 20, 2026, Lacy was released by the Royals, having not made an appearance during the season. ==Personal life==