Derbyshire elite performance director Graeme Welch has resigned after two and a half years in charge.
The 44-year-old signed a three-year deal in January 2014 to lead a revamped management set-up.
Derbyshire are second from bottom of Division Two of the County Championship with two defeats and five draws from their opening seven matches.
Elite performance coach John Sadler will take charge, supported by captains Billy Godleman and Wes Durston.
Chairman Chris Grant said: "Whilst results have been disappointing, Graeme leaves with stronger foundations in place.
"We have seen a number of players develop under Graeme's guidance. We have also seen a clear increase in the levels of professionalism and work ethic."
Derbyshire finished second from bottom in the Championship in 2015 with just three wins from their 16 matches, while they failed to progress beyond the group stages of both one-day competitions.
Welch added: "I have thoroughly enjoyed my time at the club and learned so much.
"I would particularly like to thank the chairman and board for their support over the last few years and I wish them all the best for the future."
Derbyshire face Leicestershire at home in the T20 Blast on Friday.