He played in Major League Baseball (MLB) for the Milwaukee Brewers, Minnesota Twins, Washington Nationals, Chicago Cubs, Miami Marlins, and Philadelphia Phillies.

The Padres selected Kintzler in the 40th round of the 2004 MLB Draft, and he spent two years in the team's farm system before sustaining a season-ending shoulder injury.

Joyce took one year off from baseball and moved back home to undergo shoulder surgery before he was recruited to the independent Winnipeg Goldeyes in 2007.

The Brewers offered Kintzler a contract in 2009 after watching him pitch at the American Association All-Star Game for the Saints, and he made his MLB debut in September 2010.

Kintzler's five-season tenure with the Brewers was hindered by injury, first a stress fracture in his elbow in 2011, followed by a patellar tendon rupture in 2014, and he became a free agent at the conclusion of the 2015 season.

Kintzler accepted a minor league contract with the Twins that December, and became the team's closer in 2016 after the departure of Kevin Jepsen.

Kintzler continued to close for the team in 2017 after Glen Perkins experienced a shoulder injury, and he received an All-Star selection in 2017.

Kintzler signed a one-year contract with the Marlins in 2020, and helped lead the team to the postseason by throwing shutout final innings in both Wild Card Games against the Cubs.

[5] In his one season with the PCC baseball team in 2003, he was an All-South Coast Conference first-team selection, with a 5–3 win–loss record and 3.83 earned run average (ERA) in 106 innings pitched.

[6] The following year, he attended Dixie State College, where he posted a 9–1 record and 2.30 ERA in 12 starts, and helped led the team to the 2004 NJCAA National Baseball Championship.

[13][14] Rather than pitch that year, Kintzler instead moved back to Las Vegas, received shoulder surgery, and worked at Cold Stone Creamery, which he joked, "[g]ives you a strong wrist".

[13] The shoulder surgery limited his four-seam fastball to 86 mph (138 km/h), and Kintzler worked with Greg Maddux to develop a two-seam sinker.

[13] In the offseason, Kintzler requested a trade to the St. Paul Saints of the American Association, believing that the team gave him a better chance of making the major leagues.

[15] While playing with the Saints in 2009, Kintzler was offered the role of former Oakland Athletics pitcher Tim Hudson in the film Moneyball.

[16][17] Kintzler signed a minor league contract with the Milwaukee Brewers on July 24, 2009, the day after his All-Star appearance.

[14] He spent time with the Class-A Advanced Brevard County Manatees, Huntsville, and Nashville before being called back up to the Brewers in September, where he posted a 3–0 record and 3.78 ERA in 14 games.

He posted a 2.69 ERA in 71 relief appearances that season, retired 52 of the first batters he faced, and stranded 16 out of 21 inherited runners.

[36] The next day, regular closer Kevin Jepsen was released from the team following a disappointing performance, and the Twins announced that Kintzler would share the final-inning position with Fernando Abad.

[38] With Perkins beginning the 2017 MLB season on the 60-day disabled list as he recovered from shoulder surgery, the Twins named Kintzler as their closer.

[41] On July 31, 2017, the Twins traded Kintzler to the Washington Nationals in exchange for minor league pitcher Tyler J.

[43] Kintzler served as the club's seventh-inning reliever, setting up for Ryan Madson and Sean Doolittle in the eighth and ninth, respectively.

[53] After acquiring Kintzler from the Nationals, Cubs manager Joe Maddon praised the pitcher, calling him a "very durable kind of guy [...] Good sink.

[58] He was placed on the 10-day injured list in August with a sore pectoral,[59] and missed a handful of games in September due to an oblique strain.

"[62] Kintzler played a critical role in the Marlin's postseason run, throwing scoreless final innings in both Wild Card Games against the Cubs.

[65] On February 10, 2021, Kintzler signed a minor league contract with the Philadelphia Phillies, a deal that included an invitation to spring training.

[67] Kintzler debuted with the Phillies on April 5, 2021, taking over for starting pitcher Matt Moore in the fourth inning of an eventual 5–3 rout over the New York Mets.