He has previously played in Major League Baseball (MLB) for the Boston Red Sox and Washington Nationals.

[6] Downs spent the 2018 season with the Dayton Dragons of the Single-A Midwest League[7] where he hit .257 with 13 home runs, 47 RBI, and 37 stolen bases in 120 games.

[8] On December 21, 2018, the Reds traded Downs to the Los Angeles Dodgers, along with Homer Bailey and Josiah Gray in exchange for Matt Kemp, Yasiel Puig, Alex Wood, Kyle Farmer and cash considerations.

[13] The Dodgers promoted him to the Double-A Tulsa Drillers of the Texas League on August 20, 2019,[14] where he hit .333 in 12 games with five home runs and 11 RBIs.

[15][13] The Dodgers traded Downs, Alex Verdugo, and Connor Wong to the Boston Red Sox in exchange for Mookie Betts, David Price and cash considerations on February 10, 2020.

In May, he was named to the roster of the Colombia national baseball team for the Americas Qualifying Event for the Olympics.

[25] Downs made his MLB debut two nights later, playing third base and going 0-for-4 at the plate against the Detroit Tigers at Fenway Park.

[28] That evening, Downs collected his first MLB hit and RBI, and then scored the winning run in the bottom of the 10th inning against the New York Yankees.

His lone RBI came on a walk-off single against the Oakland A's on August 13 to cap a ninth-inning comeback from a 7–2 deficit.