Didn't the Rangers basically go through decades of administrative corruption, ballooning debt, and tax evasion before even getting to that point?
Tax evasion...? Their debt wasn't unmanageable. The holding company, Murray International Holdings, took a massive hit with the global collapse of the economy. Then you had the HMRC, the UK IRS, decided to file suit under the theory that a tax avoidance scheme was illegal (a case Rangers won, was appealed and then Rangers won again). However, Murray had sold the team off to Whyte who just ran it into the ground before those cases were closed. HMRC was using Rangers as a test case before attempting to go after EPL teams that were using the same policies.
However, none of that has to do with how the fans responded to the rise of Mike Ashley and his bid to take over the team. The fans revolted and boycotted games. They refused to purchase jerseys and other items (Ashley owns SportsDirect and has the rights for selling Rangers gear). Ultimately, it was hitting them in the wallet that turned the tide and enabled Dave King, a fan of the team and someone that sat on the board previously, to come into power.