jemagee,
If Donaghy gave the feds nothing of importance, his sentence would be much, much, much stiffer, I think. His cooperation, to this point, hasn't produced anything of real relevance. So why is he getting a light sentence? To my line of thinking, it means something that he's given up HAS NOT been made public yet. And if there's something to that, it makes it look less favorable to David Stern's claim that this is just one rogue referee. And if it isn't just one rogue referee, you'd think Stern would know that by now - which makes his other claims look like lies.
Donaghy's light sentence reflects badly on Stern - either because there's more to the story, or because corrupt officiating isn't really that bad. Both are damaging to Stern.