I don't see how having a top three and an average could be a bad thing.
Because having a total average stat would just renew the pressure that this change is set to relieve. If you have a stat, people are bound to want to have theirs high. If you want to find good artists and aren't happy with the top three rule, you should just follow decent submissions.
Ok, so just make the top-3 statistic the more important one (make it stand out in bold or something). See, the flip side of the coin is that artists now feel that everything besides those three top submissions no longer counts... it gives them less incentive to submit consistently good quality work. Although some Newgrounds artists (like Zekey) definitely benefit from this system because their scores are all over the spectrum, other people lose out. The viewer loses out too, because now when I look at someone's "average" I have no idea what their actual average quality of work is.
Actually, perhaps a solution to that last problem would be to allow us to see the ratings of someone's submissions inside the drop-down menu. That could be REALLY usefull, because if I see someone on Newgrounds with 50 submissions I have no idea which one to click - there's no way to tell which ones are good... the names don't give any hints about the quality (well, usually).
But in all seriousness, fixing the audio portal is much more important for me than any of this stuff. The flash portal, despite its minor faults here and there, actually works very well on the whole. The audio portal, on the other hand, has some major faults that are easily fixed and should have been fixed long ago. The solution is to simply make the audio portal like the flash portal... make it have the same features that work so well on the flash site, like favourites, allowing us to see our reviews, batting averages for authors, etc.
I for one think that the audio portal has the potential to be the equal of the flash portal - I've seen someone from there being hired to write music after their submissions were noticed by a band conductor. A lot of the composers there are top-notch and deserve a system that will make it easy for visitors to remember their names and their music. Some of the stuff there doesn't sound like it was ever meant to be attached to a flash submission - the audio portal may have begun as a way for flash animators to find copyright-free pieces of music, but it's grown beyond that.