The fact is the Coalition is making steady progress in Iraq, but not without ups and downs. War is a terrible thing and terrible things happen during wars, even when you are winning. In war, as in any contest of wills with capable opponents, things do not always go as planned; the guys with the white hats don't always come out on top in each engagement. That doesn't mean you are losing. Sure, there are some high profile and very spectacular enemy attacks taking place in Iraq these days, but the great majority of what is happening in Iraq is positive. So why is it that no matter what events unfold, good or bad, the media highlight mostly the negative aspects of the event? The journalistic adage, "If it bleeds, it leads," still applies in Iraq, but why only when it's American blood?
Short answer: it confirms what they believe (and probably what their editors want to receive), regardless of the facts.
Update: Blackfive has it, too, with a longer quote. Update to update: Actually B5 had it first.