San Francisco Giants Minor leagues (2007–09) Runzler spent most of the 2007 season with the Rookie-level
Arizona League Giants. In 15 games, he had a 1–2
record, a 3.44
earned run average (ERA), 24
strikeouts, six
walks, and 15
hits allowed in
innings pitched. He also appeared in one game for the
Single-A short season
Salem-Keizer Volcanoes of the
Northwest League, allowing one
run in one inning of work. He did not allow a run in his first 15 games with San Jose; combined with his last appearances with Augusta, Runzler threw consecutive scoreless innings.
Major leagues (2009–12) On September 4, 2009, Runzler made his MLB debut against the
Milwaukee Brewers, striking out center fielder
Jody Gerut on three pitches. With that appearance, Runzler became the first player in Giants' history to play minor league baseball at four levels and appear in the major leagues in the same season. He had a 5.00 ERA through May 26, but in his next 16 games through July 8, Runzler allowed just one earned run. In the July 8 contest, against the Brewers, Runzler entered the game with one out in the sixth, the bases loaded, and San Francisco clinging to a 6–3 lead. He got through the inning without allowing any runs to score, then received a chance to have his first MLB
at bat in the bottom of the inning, as manager
Bruce Bochy wanted him to pitch in the seventh inning as well. Facing
David Riske, Runzler fouled a ball off his knee. Unable to finish the at bat, he was placed on the
disabled list with a fractured left patella. He returned in September and made five more appearances, allowing no runs. Runzler began the 2011 season with the Giants but struggled, posting a 6.41 ERA in his first 18 games. On May 28, he was optioned to Fresno to make room for Casilla, who was activated from the disabled list. While he was in Fresno, the Giants used him as a starting pitcher, though sportswriter
Andrew Baggarly thought the move was a temporary one meant to get him more time on the mound. On August 16, Runzler was recalled when
Sergio Romo was placed on the disabled list. Runzler was called on to make a spot start on August 21 after
Jonathan Sánchez was injured. He gave up four runs in only innings against the
Houston Astros, but the Giants ultimately won 6–4 in 11 innings. Afterwards,
Eric Surkamp was called up to join the rotation. Both pitchers were sent to Fresno on August 28 to make room for Romo and
Andrés Torres to return from the disabled list, but they were recalled on September 6 after rosters had expanded. In 17 games (10 starts) for Fresno, Runzler had a 2–3 record, a 3.98 ERA, 59 strikeouts, 32 walks, and 47 walks in 52 innings. In 31 games, he had a 1–2 record, a 6.26 ERA, 25 strikeouts, 16 walks, and 29 hits allowed in innings pitched. Runzler consulted sports physician
James Andrews, who determined that surgery for the injury was unnecessary. He pitched in six games without allowing a run, striking out five, walking three, and allowing one hit in innings. After the season, Runzler pitched for the
Scottsdale Scorpions of the
Arizona Fall League. In 10 games, he had a 1–1 record, a 3.38 ERA, 11 strikeouts, seven walks, and six hits allowed in eight innings. In 51 games for the Grizzlies, he had a 3–7 record, a 5.68 ERA, 50 strikeouts, 37 walks, and 58 hits allowed in innings. Runzler was invited to spring training in 2014 but returned to Fresno to start the season. Runzler did not appear with Orix's main club, but did appear in six games in the Japan Western League. He registered a 4.50 ERA with 10 strikeouts in 10 innings pitched. He then signed with the
Sugar Land Skeeters of the
Atlantic League of Professional Baseball. In 33 games, he had an 0–1 record, a 1.95 ERA, 29 strikeouts, 10 walks, and 36 hits allowed in innings. He did not allow a run in his first six outings, then gave up two runs in of an inning against the
Washington Nationals on September 29. In Pittsburgh's last game of the year, on October 1, Runzler got two outs in the ninth and would have finished the inning, but an
error by
José Osuna allowed
Wilmer Difo to reach, and Runzler gave up two runs before
George Kontos entered to get the last out. Pittsburgh still won 11–8. In eight games for Pittsburgh, Runzler had no record, a 4.50 ERA, four strikeouts, two walks, and seven hits allowed in four innings pitched. However, he was released on March 11. He spent the 2018 season with the Skeeters again. In 53 games, he had a 4–2 record, a 2.81 ERA, 58 strikeouts, 27 walks, and 46 hits allowed in 48 innings. He was assigned to the
Pawtucket Red Sox of the International League on April 3. In 22 games, he had a 1–1 record, a 5.40 ERA, 22 strikeouts, 15 walks, and 26 hits allowed in innings pitched. On March 5, 2021, Runzler was released by the Sultanes. ==Coaching career==