Head coach Dave Baldwin has left Preston Grasshoppers to become the forwards coach at Leeds Carnegie.
The former Sale lock, 46, departs Lightfoot Green to take up a full-time position with the Championship club.
"It's disappointing because Dave has brought us on massively in the last couple of years," committee member Gareth Dyer told BBC Radio Lancashire.
"Obviously to go to Leeds is a massive opportunity for Dave and he leaves a hole for us to fill."
Dyer continued: "He's a very proud Yorkshireman and, once Leeds made an approach, it was the one club that he has a real affinity for. It was a massive draw for him.
"Dave's words were 'if it had been any other club, I probably would have stayed with Preston', but the draw of going home was obviously too big to turn down.
"The way we finished the league campaign and winning the Lancashire Cup has given us a real momentum that we were looking to build on for next season."