Kenley Geronimo Jansen (born September 30, 1987) is a Curaçaoan professional baseball pitcher for the Detroit Tigers of Major League Baseball (MLB). He has previously played in MLB for the Los Angeles Dodgers, Atlanta Braves, Boston Red Sox, and Los Angeles Angels. He has represented the Netherlands national baseball team in international competition.
Signed by the Dodgers as an undrafted free agent in 2004, Jansen converted from a catcher to a relief pitcher in the minor leagues and made his major league debut in 2010. He served as the Dodgers' closer starting in 2012, and led the National League (NL) in saves in 2017 and 2022. After 11 years with the Dodgers, he entered free agency and signed a one-year deal with the Braves in 2022. He then signed with the Red Sox.
Jansen is a four-time MLB All-Star and two-time NL Reliever of the Year (2016, 2017). In 2019, Jansen became the 30th pitcher to reach 300 career saves. In 2023, he became the seventh pitcher to total 400 career saves. He also is a member of 450-save club, having reached that on April 8, 2025.
Jansen was born in Willemstad, Curaçao, the youngest of three sons of Isidor and Bernadette Jansen. His father worked in construction until suffering a stroke when Kenley was 12. His mother was a travel agent. Jansen grew up as a Braves fan because the team's games were broadcast in Curaçao on TBS. The team signed fellow Curaçaoan Andruw Jones and Jansen's older brother Ardley. Kenley Jansen began playing baseball at the age of six, alongside his older brothers. He began as an outfielder before moving to shortstop. Jansen then met Andrelton Simmons and was shifted to third base. He later played first base and catcher.
Jansen was signed as an undrafted free agent catcher by the Dodgers organization on November 17, 2004 and was assigned to the Rookie Class Gulf Coast Dodgers. He played in 37 games and hit .304 before being promoted to the Ogden Raptors of the Pioneer League on August 26. He had two hits in 11 at-bats in three games for Ogden. He was back with the Gulf Coast Dodgers the following season, hitting .245 in 35 games. After the season he played for the North Shore Honu in the Hawaii Winter Baseball League, where he hit .121 in nine games.
Jansen split 2007 between the Raptors and the Class-A Great Lakes Loons of the Midwest League, hitting .207 in 73 games. After the season, he again played in Hawaii Winter Baseball, this time for the West Oahu CaneFires In 2008 with the Loons, he hit .227 and nine home runs in 79 games. He was selected to the mid-season Midwest League All-Star game.
In 2009, he was the starting catcher for the Netherlands team in the World Baseball Classic. In the Netherlands' upset of the favored Dominican Republic team, Jansen threw out Willy Taveras on an attempted steal of third base in the ninth inning, a key play in the game. He began 2009 with the Inland Empire 66ers of San Bernardino, but hit just .202 in 38 games. Despite that, he appeared in eight games for the Triple-A Albuquerque Isotopes but had just five hits in 27 at-bats.
The Dodgers convinced Jansen that he had no future at catcher because of his poor offensive numbers and that he should switch to pitching. Under the tutelage of former major leaguer Charlie Hough, he made the conversion in the second half of the 2009 season at Inland Empire. He pitched 11+2⁄3 innings for the 66ers, allowing six earned runs. He continued the conversion in the Arizona Fall League for the Peoria Javelinas.
Jansen was added to the Dodgers 40-man roster on November 19, 2009. He started with Inland Empire again and allowed only five runs in 18 innings while striking out 28 batters. On May 15, 2010, he was promoted to the Double-A Chattanooga Lookouts, where he was selected to the mid-season Southern League All-Star Game. He pitched 27 innings in 22 games for the Lookouts with a 1.67 ERA.
Los Angeles Dodgers (2010–2021)
On July 23, 2010, Jansen was promoted to the Dodgers. He made his Major League debut in relief on July 24 against the New York Mets, where he pitched a scoreless inning, retiring all three batters he faced and striking out two. On July 25, Jansen recorded his first Major League save, when he pitched a 1-2-3 inning against the Mets.
On August 26, Jansen walked and scored a run in his first Major League plate appearance, in Milwaukee against Yovani Gallardo of the Brewers. He collected his first major league hit on August 31, a single up the middle off Kyle Kendrick of the Philadelphia Phillies. Jansen recorded his first win against the Houston Astros on September 11. He appeared in 25 games with the Dodgers in 2010, working 27 innings with a 1–0 record and a 0.67 ERA. He also saved four games in 2010.
In 2011, Jansen became a key member of the Dodgers' bullpen. He was 2–1 with a 2.85 ERA in 53+2⁄3 innings and saved five games. Jansen also struck out 96 batters, setting a new Major League season record with 16+1⁄3 strikeouts per nine innings.
In May 2012, Jansen became the Dodgers' closer after Javy Guerra struggled in the role. At the end of the season, after missing some time due to heart problems, Jansen was replaced as closer by Brandon League. He appeared in 65 games, compiling a 5–3 record, 2.35 ERA, 99 strikeouts, and 25 saves.
Jansen began 2013 as the setup man in the bullpen but resumed the role as closer when League struggled. He pitched in 75 games with a 4–3 record, 1.88 ERA and 28 saves. He did not allow any runs in three appearances in the 2013 National League Division Series (NLDS) against the Atlanta Braves but was less effective in the Championship Series (NLCS) against the Cardinals, allowing two runs in two innings.
On February 11, 2014, Jansen avoided his first arbitration hearing by signing a $4.3 million contract with the Dodgers. Fully established as the Dodgers' closer in 2014, Jansen worked in 68 games with a 2.76 ERA, 101 strikeouts and 44 saves. He became just the fourth Dodger pitcher in history with at least 40 saves in a season, joining Éric Gagné (who did it three times), Todd Worrell, and Jeff Shaw. Jansen only pitched one inning in the NLDS against the Cardinals.
On January 16, 2015, Jansen again avoided arbitration, signing a one-year $7.425 million contract with the Dodgers. However, on February 17, he underwent surgery to remove a growth from a bone in his left foot. The recovery time kept him out of action until May. Jansen was eventually activated off the disabled list on May 15 and rejoined the Dodgers. Jansen struck out 23 batters in his first 14 games of the season, without giving up a walk. This broke Jay Howell's team records, set in 1991, of 13 games without a walk to start a season and 20 strikeouts without a walk to start a season. Jansen eventually struck out 27 before he finally walked a batter on June 30, eight shy of the major league record. He made 54 appearances for the team in 2015 with a 2.41 ERA and 36 saves. He struck out 80 batters while only walking 8 all season. He became the first Dodgers pitcher with five seasons of 80 or more strikeouts in relief. He appeared in three games, with two saves in the 2015 NLDS and did not allow a run in 3+2⁄3 innings.
In his final year of arbitration, Jansen signed a one-year, $10.65 million, contract with the Dodgers on January 15, 2016. On June 20, Jansen picked up his 162nd career save against the Washington Nationals, breaking the Dodgers franchise record, previously held by Gagné. He was also selected to the National League team for the 2016 All-Star Game, his first all-star selection. On August 24, Jansen tied Jim Brewer's franchise record with 604 strikeouts by a reliever. In 71 games, he was 3–2 with a 1.83 ERA and 47 saves and earned the National League Reliever of the Year Award. Of all MLB pitchers, he held right-handed batters to the lowest batting average, .107 (in 30 or more innings). In the 2016 NLDS against the Washington Nationals, Jansen pitched in four games and worked 5+1⁄3 innings, allowing four runs and saving two games. In the 2016 NLCS against the Chicago Cubs he pitched 6+1⁄3 innings over three games, with one save, and struck out 10 while only allowing one hit.