Letsch never played professional football. He started his coaching career at VfB Oberesslingen/Zell as playing coach.[1] In July 2001 he became manager of Stuttgarter Kickers's second team until 2002, but was also a part of the first team staff until the end of the 2002–03 season. Then he moved to FC Union Heilbronn and was the manager for one season. From January 2005 until July 2007, he was the assistant manager of SSV Ulm 1846.[2] From January 2008 to June 2009, he was the manager of SG Sonnenhof Großaspach.
FC Red Bull Salzburg, FC Liefering
In July 2012 he went to Salzburg and managed the under-16 team of FC Red Bull Salzburg. September 2012 he was also appointed as football director of academy.[3] In the following season, he was promoted to first team assistant manager.[2] In July 2014 he became manager of the under-18 squad.[4] In the time with the under-18s he was also the assistant coach for FC Red Bull Salzburg. In December 2015 after Peter Zeidler was sacked, he was for two matches head coach of Salzburg. In the 2015–16 season he also managed the team of FC Red Bull Salzburg in the UEFA Youth League. In June 2015 he became manager of FC Liefering in the Second League.
FC Erzgebirge Aue
On 18 June 2017 Erzgebirge Aue named Letsch as their new manager on a three-year contract.[5] After three games Aue sacked Letsch due to poor form and results.[6]
FK Austria Wien
On 27 February 2018 he became manager Austria Wien in the Austrian Bundesliga.[7][8] He was sacked on 11 March 2019.[9]
Vitesse Arnhem
On 26 May 2020 he became the new manager of Vitesse Arnhem. The club went on to secure fourth place in the Eredivisie and reched the final of the Dutch Cup (which was lost 2–1 to AFC Ajax). They were qualified for the UEFA Europa Conference League.
VfL Bochum
In September 2022, he left Arnhem and moved to VfL Bochum. [10] He took over the team after the seventh matchday when they were in last place in the table with one point He led them to direct relegation with a 3-0 win against Bayer Leverkusen on the last matchday.