Dietrich will replace Kirk Sarloos, who left after one season as the pitching coach with the Titans to take the same job at TCU.
"It was a whole whirlwind thing that came out of nowhere," Dietrich said of the offer from Titans Coach Rick Vanderhook, which he accepted Tuesday night. "There was no one specific thing [behind the move]. But I felt the opportunity Vanderhook presented me was something I wanted. This was not a move that was lateral. This was a move forward and a progression in my career."
Dietrich earned praise from UCI Coach Mike Gillespie for helping the Anteaters produce a 2.95 team earned-run average in 2011, his first season working with the pitching staff. He spent three seasons as director of operations at UCI before replacing Ted Silva, who left following the 2010 season to become pitching coach at Loyola Marymount.
The 2.95 ERA in 2011, when new bat restrictions lowered offensive production across the country, was the lowest for a UCI team since 1974. He was also credited for helping then-junior Matt Summers emerge from an inconsistent reliever the season before to become the Big West Conference Pitcher of the Year. Summers also made some All-American teams and was drafted in the fourth round by the Minnesota Twins.
UCI went to the 2011 Super Regionals, in which the 43-18 team was three outs away from advancing to the College World Series for the second time before losing at Virginia, the No. 1 national seed.
UCI, however, went 31-25 and missed the postseason for the first time in seven seasons in 2012. The pitching staff posted a 3.25 ERA, led by first-team all-conference sophomore Andrew Thurman.
Both Summers and Thurman threw no-hitters under Dietrich's tutelage.
Gillespie said late last week that he expected his coaching staff to remain intact for the 2013 season.
Dietrich spent four years pitching in the Colorado Rockies organization after being drafted out of Pepperdine. He also played at Santa Ana Community College.
His coaching career included stops as a pitching coach at Cal State Los Angeles, Los Angeles City College and Arcadia High.
He earned a bachelor's degree in criminal justice from Cal State Fullerton in 1999.
Brett Smith, a former UCI mound standout who was a second-round pick by the Yankees in 2004 and has been the team's undergraduate assistant the last two seasons, is someone who may be considered as a successor. The position is, however, expected to generate widespread interest.