I think 1234 meant, stylistically, they were pretty much a "big rock/hard rock" band on the first five.
The departure tunes, like Big Bad Bill, were kinda there as filler tracks or little intermissions.
The meat of each record was mainly the "big rock" tunes.

Though i do hear tonal variations on the first six, Eddie still sounded like HIS sound.
It always was "brown."
It might be brighter or darker, but it was still that early VH sound.

By 5150, it was a totally new thing.
1984 had the last traces of that signature EVH tone.