Simon Evans left the team, taking up the reins of a Mitsubishi Lancer Evolution IX under the banner of his own personal building business.
Despite this setback, Evans and his wife Sue regained the title they had lost the previous year to their now former boss.
Bates could only manage third in the title, finishing behind one of the Corollas he had previously built to the Group N+ regulations, driven by an ever-consistent Glen Raymond.
Evans younger brother Eli slipped to fourth in the standings after beating Simon into second position last year.
The sixth, the newly reinstated Rally Australia, will contribute only to the manufacturers standings.