A lot seemed to be missused the main ones who come to mind are the obvious like Guerrero, Malenko, Benoit, Mysterio etc but also other established stars like Bret Hart, Davey Smith and Jim Neidhart were main eventing WWE before they left then in WCW Smith and Neidhart almost became jobbers with Bret's talent completely wasted.
Mike Awesome's run as ECW champion was incredible then he went to WCW and became almost a joke dressing up as some reject from the 70's.
Sabu was one of the hottest wrestlers during the early 90's in Japan and ECW and when he came to WCW with the orginal Sheik I had such high hopes only for him to last about 3 or 4 weeks.
I think WCW in the late 90's had way too much talent, They could not feature everyone all of the time. WCW in fairness wasn't all bad as in this period of time for the one and only time WCW had overtaken the WWE as my favourite wrestling company and with the monday night wars it was probably the best time ever to be a wrestling fan.