Hi Jason,
If this were SQL, what you're after is a "TOP" function...but alas, it is not available (yet).
So as a hack...
Depending on where that user's name count is coming from, if you can persist it as custom data (e.g. in a calculated parameter), you could then filter on it (e.g. >4), and sort on it (e.g. descending on that count), and chart it.
Regards,
Doug