[4] Sanmartin split the 2018 season between the Low-A Staten Island Yankees, the Single-A Charleston RiverDogs, the High-A Tampa Tarpons, and the Double-A Trenton Thunder.

[2] On January 21, 2019, Sanmartin and Sonny Gray were traded to the Cincinnati Reds in exchange for Shed Long Jr. and draft pick compensation.

[5] Sanmartin split the 2019 season between the High-A Daytona Tortugas, and the Double-A Chattanooga Lookouts, going a combined 4–12 with a 4.05 ERA and 114 strikeouts over 122+1⁄3 innings.

[7] Sanmartin split the 2021 minor league season between Chattanooga and the Triple-A Louisville Bats, going a combined 10–2 with a 3.32 ERA and 112 strikeouts over 100+1⁄3 innings.

Sanmartin spent the 2022 season mainly working out of the Reds' bullpen, making 45 appearances (4 starts) and registering a 4–4 record and 6.32 ERA with 47 strikeouts in 57.0 innings pitched.