He wanted to find guys like a Ben Smith to show them they could obtain Central Districts honours while being based here.
"It's trying to get a few younger guys back and playing in Wanganui, and getting them prepared for cricket beyond Wanganui."
WCA chairman Stu Gill said Gillespie will combine with Raj to coach the squad while WRFU rugby development officer Justin Lock remains manager.
"The trio bring a wealth of experience to coach and mentor our young team in the Hawke and Chapple Cup."
Gill said Bannister "doesn't believe he can give the role with WCA the input that he has this past season". He said the WCA board thanked Bannister for his enthusiasm and wished him well in his new ventures.
Both Raj and Bannister said the change in coaching was not a result of the red-faced situation with Otago Cricket last week, when Otago CEO Mike Coggan rejected Bannister's announcement his client Christi Viljoen would be joining the Volts on a first-class contract.
"It's totally separate, that's a whole different discussion," Bannister said.
"Those things can be rectified with communication and understanding. I can't do the rep job and give the Cricket 6's the energy it needs. One thing had to go. It's not my time and I want to commit to other things."
Raj also said the departure had "absolutely nothing to do" with those issues.
"It's more that Rod has stepped down and has other commitments. A new contract was put in front of him but he didn't feel he had the time.
"It caught me by surprise, but I know there was a period where Martin [Inness] and Stu Gill were chatting with Rod [about leaving]."
Bannister reiterated his belief that for Wanganui to be successful at representative level, the WCA needed to approach professional-level players so one each could play with the city clubs United, Tech and Marist, who would also have to contribute financially.
Gillespie has also acknowledged he would like to bring an outside player into the fold.
"I need to sit down with Wanganui Cricket and see what their plans are on that. Having played in England for a couple of seasons, I do have contacts."
After spending the last few seasons focusing on youth cricket in Wanganui, Raj said he will handle the logistics for Gillespie, with the first get-together for players being in June, ahead of the season start in October.