Willrich, a native of Koblenz, Germany, began playing club soccer and played professionally in his home country before joining Dutch First Division club PSV Eindhoven during the 1977–1978 season. That season Eindhoven won the UEFA Cup, but Willrich made only three first team appearances.
In 1978, Willrich moved to the United States and signed with the San Diego Sockers of the NorthAmerican Soccer League. The Sockers had played the 1977 NASL season as the Las Vegas Quicksilvers before moving to San Diego and changing its name to the Sockers. In 1979 and 1980, the Sockers negotiated a deal with the México Primera División Association football clubUNAM Pumas to exchange players during the offseason. The Mexican league played in the fall, winter and early spring while the NASL played in the spring and summer. As part of this exchange, Willrich spent time with UNAM in 1979 and 1980. During its years playing outdoor soccer in the NASL, the Sockers were a decent, but not dominant team. The NASL introduced an indoor soccer season in 1979–80, however San Diego did not participate. The following indoor season 1980–81, was the Sockers' first. That year they failed to qualify for the playoffs but the next year where it again won the 1982–83 MISL championship. The next year, the NASL ran its last indoor season and the Sockers took that title as well. Willrich was named MVP of the 1984 Indoor Championship Series having scored 7 goals in the three-game sweep of New York. At the end of the 1984 outdoor season, the NASL collapsed and the Sockers moved permanently to MISL. Willrich remained with the Sockers through all this, growing into a powerful and reliable forward. In his first season with the team, he scored nine goals in thirty games. While that was a decent number, he blossomed when playing indoors. During the Sockers run to the 1980–1981 NASL indoor title, Willrich was second in team scoring with sixteen goals. He continued to enjoy a scoring touch as he helped the Sockers to 6 consecutive indoor titles through the 1987–1988 season. The San Diego Sockers inducted Willrich into its Hall of Fame.
He also played with the Wichita Wings from 1990 to 1992.
U.S. Olympic team
While with the Sockers, Willrich gained his U.S. citizenship. In 1984, he was selected for the U.S. Olympic soccer team which competed at the 1984 Summer Olympics in Los Angeles. In the first game, against Costa Rica, Willrich both scored and assisted on a goal in the U.S. victory. Despite this achievement, he was never called up to the full U.S. national team.
