On July 24, 2017, the Royals traded Ruiz, Matt Strahm and Travis Wood to the San Diego Padres in exchange for Trevor Cahill, Ryan Buchter and Brandon Maurer.

[8] He made his major league debut that day as the starting center fielder against the Colorado Rockies, going 2-for-4 with an RBI.

[9] On August 1, 2022, the Padres traded Ruiz, Taylor Rogers, Dinelson Lamet and prospect Robert Gasser to the Milwaukee Brewers for Josh Hader.

[13] On March 25, 2023, manager Mark Kotsay announced that Ruiz had made the Opening Day roster.

[14] While playing against the New York Yankees on June 28, Ruiz was the final out, grounding out to Josh Donaldson, in Domingo Germán's perfect game.

[20] In 29 games for Oakland, Ruiz slashed .200/.270/.382 with two home runs, eight RBI, and five stolen bases.