What does that mean exactly? Good question. But first the particulars, from John Baer's column in the Philly Inquirer:

Hillary Clinton's presidential campaign failed to file a full slate of convention delegate candidates for Pennsylvania's April 22 primary.

This despite the possibility the primary proves critical and despite Clinton owning the full-throated support of Gov. Rendell, state Democratic Party leadership, Mayor Nutter and, presumably, the organizational skill all that entails.

And despite a Rendell-ordered extension of the filing deadline that could be viewed as more than just coincidental. [snip]

It appears Clinton came up 10 or 11 candidates short across a number of congressional districts, including two in Philadelphia.

That's close to 10 percent of the 103 delegates to be decided by voters.

It appears the shortage would've been double that if Rendell hadn't extended last week's candidate filing deadline by a day and a half, ostensibly due to bad weather.

This at a time when Clinton's campaign, like Barack Obama's - which did file a full slate in the state - hoards delegates like diamonds.

Another example of the Clinton camp dropping the ball? Well, not exactly.

But Clinton's faux pas is more of an image problem than a practical one.

Under Democratic Party rules (and does any organization on the planet have more rules or more complex rules?) a presidential candidate winning in a congressional district gets delegates from that district (assigned at a later date) whether he or she files slates delegates or not.

But, as Baer writes, it's the image, stupid: "For a national campaign stressing competence, experience, "ready day one," one might expect a full slate in what could be a key state." Not the kind of thing you want voters reading, no matter the practical implications, when you're trying to paint the other guy as inexperienced.