From Costa Mesa, California, Maurer pitched in Little League Baseball and high school at Orange Lutheran High School. The Mariners selected Maurer in the 23rd round of the 2008 MLB Draft. After being overshadowed by other prospects, Maurer had a strong spring training showing with the Mariners in 2013, and made the team's Opening Day roster in the starting rotation. The Mariners traded Maurer to the Padres after the 2014 season, and he became a relief pitcher. The Padres traded Maurer to the Royals in 2017. Maurer signed a minor league free agent deal with the Pirates during prior to the 2019 season.
The Seattle Mariners drafted Maurer in the 23rd round, with the 702nd overall selection, of the 2008 Major League Baseball Draft. Rather than attend Long Beach State, Maurer signed with the Mariners. Upon joining the Arizona League Mariners of the Rookie-levelArizona League, he was able to throw as fast as 93 miles per hour (150 km/h), with the team expecting that he would increase his velocity by approximately 2 to 3 miles per hour (3.2–4.8 km/h) by adding 20 to 30 pounds (9.1–13.6 kg).[1] By 2011, Maurer could throw as hard as 96 miles per hour (154 km/h).[5]
On December 30, 2014, the Mariners traded Maurer to the San Diego Padres in exchange for Seth Smith.[17] In the first half of the 2015 season, Maurer pitched to a 2.11 ERA. His performance diminished in the second half as he suffered from shoulder inflammation.[18] Maurer's 2015 season ended with a 7-4 record and an even 3 ERA in 53 games.
Maurer entered spring training in 2016 as a candidate for the starting rotation.[19] The Padres opted to keep Maurer in the bullpen for the 2016 season.[20] The Padres named Maurer their new closer after the team traded away closer Fernando Rodney to the Miami Marlins on June 30, 2016.[citation needed] He took on the role for the rest of the season, saving 13 games. For the 2017 season, Maurer entered as the incumbent closer for the Padres. He saved 20 games for the Padres despite having an ERA of 5.72 although his fielding independent pitching (FIP) had him with a 3.23 ERA. In his three seasons with the Padres, Maurer had an 8-13 record with 33 saves.
On January 30, 2019, Maurer signed a minor league contract with the Pittsburgh Pirates organization.[22] In 8 games split between the Low–A West Virginia Black Bears and Triple–A Indianapolis Indians, he compiled a 3–0 record and 2.89 ERA with 13 strikeouts across 9+1⁄3 innings pitched. Maurer elected free agency following the season on November 4.[23]