Draft and minor leagues After his freshman year at Gulf Coast, the
Los Angeles Angels of Anaheim selected Smith in the seventh round, with the 229th overall selection, of the
2008 Major League Baseball draft. Making his professional debut with the
Orem Owlz of the
Rookie-level Pioneer League, Smith recorded 76
strikeouts while
walking only six batters. He pitched for the
Cedar Rapids Kernels of the
Class A Midwest League in 2009, and the
Rancho Cucamonga Quakes of the
Class A-Advanced California League in 2010. On July 23, 2010, the Angels traded Smith along with
Sean O'Sullivan to the
Kansas City Royals for
Alberto Callaspo. Pitching for the
Northwest Arkansas Naturals of the
Class AA Texas League in 2011, Smith and
Kelvin Herrera combined to pitch a
no-hitter on July 19, with Smith pitching the first seven innings. Smith began the 2012 season with the
Omaha Storm Chasers of the
Class AAA Pacific Coast League. By the end of the 2012 season, Smith had made 16 starts, his record was 6–9 with a 5.32 ERA. During the 2013 season, the Royals transitioned Smith into a
relief pitcher. He spent the majority of the season at Omaha. He was called up multiple times to the Royals bullpen while also making a spot start.
Milwaukee Brewers (2014–2016) Smith was traded to the
Milwaukee Brewers in exchange for
Norichika Aoki on December 5, 2013. Smith had a 1–3
win–loss record and a 3.70
earned run average (ERA) in 2014. In the May 22 game against the
Atlanta Braves, Smith was sent to pitch in relief of
Brandon Kintzler in a botched
double switch despite Smith not having warmed up in the
bullpen. Smith ended up pitching with only eight warmup pitches from the mound and gave up the go-ahead run in the same inning. On May 21, 2015, he was ejected from a game vs the Atlanta Braves for having a foreign substance on his right arm. He was suspended for eight games, pending his appeal and his suspension was subsequently reduced to six games. Smith had a 7–2 win–loss record and a 2.70 ERA in 2015. During spring training in 2016, Smith tore the
lateral collateral ligament in his knee. He returned to the Brewers on June 2. By the end of the month of July, Smith had appeared in 27 games for Milwaukee, serving as the set-up man. He had 1–3
win–loss record and a 3.68
earned run average (ERA) in those 27 appearances.
San Francisco Giants (2016, 2018–2019) On August 1, 2016, the Brewers traded Smith to the
San Francisco Giants for
Phil Bickford and
Andrew Susac. He made 26 appearances with the Giants, finishing with a 1–1
win–loss record and a 2.95
earned run average (ERA). On March 20, 2017, Smith was diagnosed with possible UCL damage in his left elbow, but no structural damage. He returned to California to seek second opinions with doctors, who petitioned that Smith would require surgery. On March 24, it was reported that Smith elected to have
Tommy John surgery on his elbow, ending his 2017 season with the Giants. In 2018, he returned to action in mid-season and was used as a
setup man and the
closer. He appeared in 54 games, finishing with a 2–3
win–loss record and a 2.55
earned run average (ERA) to go along with 14 saves (14/18 in save opportunities). In 2019, Smith was named the Giants'
closer. He was selected to the All Star Game in 2019 after he converted 23 of 23 save opportunities in the first half of the season. For the season, he was 6–0 with 34 saves (3rd in the NL) and a 2.76 ERA, and 96 strikeouts in 65.1 innings.
Atlanta Braves (2020–2022) On November 14, 2019, Smith signed a three-year contract with the
Atlanta Braves worth $39 million, with a club option for a fourth year. On July 4, 2020, it was announced that Smith had tested positive for
COVID-19. He returned to baseball-related activities on July 26, and was placed on the Braves' active roster on August 6. In 2020, he was 2–2 with a 4.50 ERA in 18 relief appearances covering 16 innings. In
2021, Smith was 3–7 with 37 saves and a 3.44 ERA in 71 relief appearances covering 68 innings. The Braves clinched a playoff berth, and in an
NLCS rematch versus the
Dodgers, he was 2–0 with no runs allowed. Smith closed out Game 6 of the
World Series versus the
Houston Astros, which Atlanta won to clinch the title. He notably did not surrender any runs in the entire
postseason over 11 appearances, going 2–0 with six saves. Smith made his Astros debut the following day versus the
Boston Red Sox, allowing a solo home run in an otherwise clean ninth inning. He appeared in 24 games for Houston but did not appear in the postseason for Houston. The Astros advanced to the
World Series and defeated the
Philadelphia Phillies in six games to give Smith his second World Series title in two seasons, making Smith the tenth player in Major League history to win back-to-back World Series with different teams. The Astros declined Smith's option for 2023, thereby making him a free agent.
Texas Rangers (2023) On March 4, 2023, Smith signed a one-year contract with the
Texas Rangers. Smith led the Rangers with 22 saves during the regular season. The Rangers defeated Smith's former team, the Astros, in the
2023 ALCS to reach the
2023 World Series. This marked Smith's third straight World Series appearance with three different teams, a feat accomplished previously by
Don Baylor and
Eric Hinske. Smith pitched two-thirds of an inning in both Game 1 and Game 4 of the 2023 World Series. The Rangers went on to beat the Arizona Diamondbacks in the World Series in 5 games, making Smith a 3-time World Series Champion in the span of 3 years with 3 different teams, the first time this has been done in World Series history and the history of North American professional sports as a whole.
Kansas City Royals (second stint) Seeking to address bullpen issues, the Royals reunited with Smith and signed him to a one-year $5 million contract on December 11, 2023. Smith served as a veteran leader that could lead younger arms in the bullpen and helped recruit other free agents to the Royals. Assigned as the team's closer, Smith struggled to start the season. He gave up 11 runs across 9.1 innings in April. Smith was not on the Royals'
2024 ALDS roster due to a back injury. The Royals lost in four games to the
New York Yankees, ending Smith's bid for his fourth consecutive championship with his fourth different team. ==Personal life==