Grewe assisted at the
University of Chicago for the 1999 and 2000 seasons. His 2000 team broke six all-time school batting records. He then served as hitting coach and worked with the infielders and catchers as an assistant coach at
Central Michigan University in 2001–2002. As hitting instructor, his 2001 team broke three all-time school records. Prior to taking over in
East Lansing, Grewe was the lead assistant coach at the
University of Notre Dame. Grewe served as recruiting coordinator for the
Fighting Irish and was instrumental in attracting two top-10 recruiting classes to Notre Dame with the 2004 class being ranked number six in the country by
Baseball America and the 2006 class being ranked number seven by Team One Baseball. His 2004 team is still the school record holder for all-time single season wins. He coached 13 players who graduated and entered the professional baseball ranks. The Irish won three straight
Big East championships and went to three straight
NCAA regionals during Grewe's tenure. In addition to his position as recruiting coordinator, Grewe worked with the catchers and hitters. Grewe was named head baseball coach at Michigan State on July 13, 2005. At age 29, he was the youngest Division 1 BCS head coach in the nation. The Spartans were 26–30 in 2006 and 25–26 in 2007. MSU's 2008 recruiting class was named tops in the Big 10 by
Baseball America. In three short years, Grewe raised over $5 million to build the current practice facilities and brand new baseball stadium. At the time, he secured the second largest single donor gift in the history of the athletic department with a $4 million donation by
Drayton McLane, garnering stadium naming rights. This was finalized just after Grewe honored McLane as the baseball program's Alumnus of the Year. Grewe and his staff recruited and coached the 2011 Big Ten Pitcher of the Year, 2011 Big Ten Player of the Year, and the school's all-time hits leader. Despite inheriting a dormant program and only amassing a 75-85 record over three years, Grewe's recruits and solid foundation led to the program's Big Ten Championship tie in 2011, the first since 1979. On June 25, 2008, it was announced that Grewe would become the new Associate Head baseball coach at
LSU, reuniting him with
Paul Mainieri. In his first year with the Tigers, Grewe coached three pitchers to All-American status, a feat never accomplished in the history of LSU baseball, and a feat that no Division 1 coach had accomplished since 2009. His 2009 pitching staff led the nation in strikeouts and were ranked #9 nationally in
earned run average. Grewe coached 21 players who went on to play professional baseball. He recruited three first-round draft picks, including an eventual
MLB All-Star Game MVP. He was the only "recruiting coordinator" in the entire country to have three consecutive recruiting classes ranked in the top 7 nationally. His 2010 recruiting class was ranked #1 in the nation by
Collegiate Baseball and #2 in the nation by
Baseball America. His 2009 team would win every championship tournament they played, including defeating
Texas at the
College World Series on June 24, 2009. ==Year-by-year head coaching record==