One of the big problems with the UFC as I see it is that these days, is there are way too many great fighters.
What I mean by this is that back in the day there used to be a bunch of good fighters who were usually great at one particular part of the sport, then there were a handfull of really great fighters who were very talented in most aspects of MMA and excellent in one or two disiplines.
These fighters because of their talent would be around year after year allowing fans to adopt heros who they could follow for a decade before they retired. These days there are so many very well rounded fighters who excel in a variety of disciplines that great fighters who stand out are getting few and far between.
On top of that the frequency of current fight schedules puts fighters at a much greater chance of either early retirement due to injury or loosing there spot due to fighting too frequently often while not fully recovered from the last match. All of these combine to assure that the number of fighters who have long careers at the top are much less than they used to be.
Just my 2 cents.