To Starship!
To Whitesnake! That's his spectacular drumming on the 1987 album. Tommy Aldridge was just used in the videos and the tour and his drumming has none of the organic (yet sophisitcated) feel Dunbar's has. The over-the-top (yet brilliant) drumming on 1987 is, however, much John Sykes' do who would sing the drum parts he envisaged to Aynsley (but credits him for doing a great job "translating" his guitarist thoughts).
The change from Bowie to Journey wasn't so radical at the time, early Journey was a Santana muso collective with jazzy instrumental forays. When Steve Perry joined for the 4th album he found that Dunbar's drumming was overly busy - Perry was a drummer himself. Legend has it that when Dunbar was late for a soundcheck, Perry took the sticks and everyone marvelled at how different the band sounded with more straightforward drumming. The writing was on the wall for Dunbar then. His successor Steve Smith was even more jazz rock-weaned but agreed to keep it simple for Journey.