I think the problem with Gorilla is that he didn't have anyone to work with towards the end that worked with him as well as Jesse and Heenan did, plus you have to think his health issues played a part as well.
Another issue was probably how the presentation changed. There was no one better in the 80s calling shows that were 90% squashes or jobber vs jobber matches and make them entertaining like he was. By the 90s, it was a different style and he didn't always fit.