Good slapstick-style humor with seemingly a biographical edge (I am a jazz fan, but know little of Mingus' real bio); that is to say, your fictional portrayal is believably written. The person who wrote this seems to be a jazz fan.
The idea of writing a parody bio of Mingus is not something everyone would do, and so you score mucho points for the choice of a challenging topic.
Prose and formatting:
You score points for prose and length. It is highly readable.
Although, what could you have placed in Uncyclopedia other than unflattering black-and-white photos of Mingus?
The addition of an info box could be a nice touch if you can manage it. (to go with the Wikipedia info box)