Never paid too much attention to how articulate a player is. Remember the character Alvin Mack in the movie The Program. The guy wasn't the brightest bulb but knew the playback front to back. Not saying that's the norm, just saying that just because a players speech isn't proper doesn't mean it translates to poor play on the field.
That being said the Ellis Lankster post game interview is an instant classic and a perfect example of which players on your team not to let get behind a mic.