Fleming, the long-term head coach of IPL side Chennai Super Kings, took part in the competition's inaugural draft in October 2019, but opted against travelling to the UK this summer. It is understood that Fleming had intended to bring his family over, but was unclear whether he would be able to do so with the country still in lockdown and decided to resign from the job.
"I'm really disappointed that I won't be coach of the side this summer but ultimately family has to come first," Fleming said. "The current global crisis has made it very difficult to travel and the extra time needed for quarantines has made it hard to get the right work/home balance. Andy is a world-class coach with experience all over the world and I'm sure the Trent Rockets men's team will have a fantastic first season of the Hundred with him behind them."
Flower, his replacement, has a growing reputation as a franchise coach. He is currently with Multan Sultans in the PSL after leading them to the top of the group stages in his first season. He has also coached Maratha Arabians to an Abu Dhabi T10 title, finished as a runner-up with St Lucia Zouks in the CPL and Delhi Bulls in the Abu Dhabi T10, and worked as Kings XI Punjab's assistant coach in last year's IPL.
Flower was involved in the Rockets' recruitment in Monday's draft, which saw them sign Timm van der Gugten and Samit Patel to complete their squad. However, it is understood that some squad members were unaware of the change of coach until Tuesday.
"Stephen will be a tough act to follow, but the guys put together a really strong squad in the original draft with a mix of international and local talent," Flower said. "We have built on it in this draft with van der Gugten and Patel joining."
Flower's appointment will reignite the debate over the absence of any British head coaches in the men's Hundred, which came in for criticism when jobs were initially offered in 2019. All eight head coaches in the men's competition are from overseas, though the majority of support staff are British.
There has also been a change of head coach in the women's competition, with Lydia Greenway stepping down from her role at Oval Invincibles. She will be replaced by Jonathan Batty, the former Gloucestershire, Northamptonshire and Surrey wicketkeeper, who was in interim charge of South East Stars in the Rachael Heyhoe Flint Trophy last summer.
It is understood that Greenway is still likely to be involved in the competition as a commentator, having previously worked for both Sky Sports and the BBC.
Matt Roller is an assistant editor at ESPNcricinfo. He tweets at @mroller98