There would still be a rebuild as a new HC & his staff would want "their guys" at different playing positions on the team. So, if a free agent became available that the new HC liked, the Bombers would sign him to replace a player already on the roster.
Maybe the new OC wants to fill the air with football & the run game then becomes secondary. Or used just to prop up the pass as in BC last year. So then, the CFL's leading rusher Brady Oliveira is suddenly not as important anymore. His salary now becomes a liability. So Oliveira is now too expensive. The OC decides to flip the roster at that position to an Amercan for a much cheaper price. So, someone like Peyton Logan takes over from Oliveira who either leaves in free agency or is traded.
Defensively, a different DC means a different scheme & players with different skill sets. So, the players there now would be replaced. That's how it works. It's all up to the new coordinators vision of what they want.
I remember when Ray Jauch took over from Bud Riley in 1978. The Bombers were a playoff team, Not a great team but always in the hunt. With a little luck going their way, a Grey Cup contender.
I believe they were 9-7 in 1978 & just couldn't win a playoff game when Riley was HC so he walked the plank. Riley just didn't seem he could get the job done & after 5 seasons of failure he was fired.
The team had a lot of talent already. Most fans & pundits thought that with Jauch's steady guiding hand & his experience, he would let that same talent rise even further to the top & with the help of scouting find even more talent to become Grey Cup winners.
Jauch kept Riley's team together for the most part in 1978. They had another decent 9-7 regular season but after another playoff exit vs the Stamps, Jauch decided to gut the team in 1979 & start over. We fell to 4-12 that year & some popular veterans were traded away or released.
Three player I remember in particular, two from Winnipeg & both popular teammates & players were gone. They were TE Leo Ezerins & SB Gord Patterson both traded in separate deals to the Ti Cats prior to the 79 season.
The other trade was a shocker as immensely popular & gregarious Lyall Woznesensky, an Canadian All Star Defensive End... "The Wizard of Woz" as he was called was traded to the Stamps for another All Star & HOFer John Helton. It was a monster trade that was so tipped in Winnipeg's favour. Helton gave the Bombers another 4 great seasons retiring in 1982. We signed Elton Brown an All Star DT from the Argos. A thousand yard rusher in RB William Miller as a free agent. Others as well.
There must have been at least a dozen changes. The Bombers missed the playoffs in 1979 but then qualified for it every year after that for over a decade. We won three Grey Cups. Those players in 1979 & 80 never got the chance to sip from Lord Earl Grey's Cup but they established a winning culture that contributed to our success in the years to come.
Jauch tried to keep things the same but it didn't work. So, he went with his instincts & really did change things up. He got rid of a lot of deadwood on the roster & recruited other players that fulfilled his vision of what a winner really was.