His screams were hardly ever in tune real falsetto screams like Ian Gillan in his heyday or Rob Halford, Geoff Tate, Sebastian Bach and Steven Tyler. DLR just made noises with his throat akin to random guitar harmonics over the melee.
I don't think they have to be necessarily. Or were intended to be.
Much like James Browns' screams.
When Sammy Hagar joined Van Halen I lost interest. Sammy doesn't have the sense of humor and the wit. Nor the swing that DLR brought to VH.
And his singing on Dreams sounds like nails on a chalkboard to me.