They don't like Romney's flip-flopping and vagueness over whether the mandate is or isn't a tax, but they also hit upon a deeper problem: 

Perhaps Mr. Romney is slowly figuring this out, because in a July 4 interview he stated himself that the penalty now is a “tax” after all. But he offered no elaboration, and so the campaign looks confused in addition to being politically dumb.

This latest mistake is of a piece with the campaign’s insular staff and strategy that are slowly squandering an historic opportunity. Mr. Obama is being hurt by an economic recovery that is weakening for the third time in three years. But Mr. Romney hasn’t been able to take advantage, and if anything he is losing ground.

The Romney campaign thinks it can play it safe and coast to the White House by saying the economy stinks and it’s Mr. Obama’s fault. We’re on its email list and the main daily message from the campaign is that “Obama isn’t working.” Thanks, guys, but Americans already know that. What they want to hear from the challenger is some understanding of why the President’s policies aren’t working and how Mr. Romney’s policies will do better.

[Emphasis mine].  The WSJ editors are right. Romney can’t “coast” in this election by simply being the anti-Obama on the economy.  One gets the strong sense that that is the entirety of the Romney strategy.  And I don't see how that can possibly work, even if the economy stays sour.

His real problem is that he can't articulate his positions lest he alienate the conservative base.  And it doesn't look like the base is going to stand by while he waffles.