JDF and Catherine Sutherland wanted to leave, and their original plan was to just have Carlos and Ashley join in their place, with Adam and Tanya leading the team. The execs wanted to clean the deck and freshen things up, though, so they basically fired the other two and they didn't even learn about it until they saw the casting call for FOUR new Rangers.
Yo Holy shit.
https://youtu.be/SAF0wcXRr_o?t=104
You can even hear how miffed he is during the power transfer.