Appointing the South African coach appeared a major coup for the Cardiff-based side, given his pedigree in the international game, but he has been unable to make his mark on The Hundred.
Fire finished seventh in the inaugural competition, above only a misfiring London Spirit, then lost all eight matches in 2022 to finish rock bottom.
Star player Jonny Bairstow has played just twice for the team since the tournament launched, while signings such as Tom Banton, David Miller and Joe Clarke have frequently under-delivered.
Meanwhile, engagement with the local area has been affected by a lack of Welsh representation.
Kirsten, a World Cup winner with India in 2011, was strongly linked with England when Chris Silverwood was sacked earlier this year but lost out to Brendon McCullum and Matthew Mott.