Milton Bradley has been described as disgruntled. Javy Lopez has the disgruntled tag now because of the Ramon Hernandez signing. Alfonso Soriano appears to be on the path to disgruntlement.
But is anyone ever "gruntled"?
The OED puts the first use of "disgruntle" in 1682. And it comes from the word "gruntle", which means "to utter a little or low grunt" and that word dates back to around 1400. And the "dis-" prefix is used as an intensifier. So someone "disgruntled" is grumbling and muttering under their breath even more than someone who just "gruntles".
Wodehouse started using the word "gruntled" in one of his books, but I'm against its use. You're risking a back formation's life!