Ruiz returned in 2021 to play for the Double–A San Antonio Missions and returned there to start the 2022 season.[7] On July 12, 2022, the Padres selected Ruiz to the major league roster.[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]
Milwaukee Brewers
On August 1, 2022, the Padres traded Ruiz, Taylor Rogers, Dinelson Lamet and prospect Robert Gasser to the Milwaukee Brewers for Josh Hader.[10] In 2022, he batted .332/.447/.526 in 437 at bats.[11] Ruiz led the minor leagues in stolen bases, with 85,[12] while being caught 14 times, and was third in the minor leagues in times hit by pitch with 27.
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. In a July 5 game against the Detroit Tigers, Ruiz stole his 43rd base of the season in the 12–3 victory. In doing so, he set the A's rookie record for stolen bases in a season, surpassing the previous record of 42 set by Mitchell Page in 1977.[15] On July 7, the A's placed Ruiz on the 10-day injured list with a shoulder injury. He was the MLB stolen base leader at the time of the injury.[16] In 132 games for Oakland, Ruiz hit .254/.309/.345 with 5 home runs, 47 RBI, and 67 stolen bases. His stolen base tally set a new AL rookie stolen base record, surpassing Kenny Lofton's 66 steals from 1992.[17]
Ruiz was optioned to the Triple-A Las Vegas Aviators on April 1, 2024.[18][19] He was recalled on April 15 after J. D. Davis was placed on the injury list.[20] In 29 games for Oakland, Ruiz slashed .200/.270/.382 with two home runs, eight RBI, and five stolen bases. He was placed on the injured list with a strained left wrist.[21] Ruiz was transferred to the 60–day injured list on September 4, ending his season.[22]