Can Clinton really believe that replacing Penn will help her campaign turn things around?

Giving Penn the boot might have helped her campaign back in January, or even February.  But given how disruptive any departure is, the Clinton campaign simply doesn't have the time or resources to retool its strategies at this late date.  As the saying goes, you don't change horses in mid-stream.  At least, you don't change horses if you still want to make it to the other side.

And therein lies the rub: Clinton is not changing strategies because she thinks it will help her secure the nomination.  She's changing strategies because her goals have changed.  

She's now running for vice-president.

Clinton and her staff know that, as things stand, she makes a poor choice for VP.  She's said things that have hurt and alienated Obama supporters, and if she's going to get the vice-president slot she needs to rebuild some bridges.  Merely conceding the race to Obama at this point is poor strategy: she needs to change her attitude while it still counts--i.e., while she's still in the race.  That is what the Penn firing is all about.  Sacking Penn (while not "really" sacking him) is an olive-branch of sorts to the Obama campaign, who sees Penn as the symbol and cause of Clinton's negative campaign.  Clinton is following this up with a change in tone for her campaign: less about Obama's negatives, and more about Clinton's positives.  It's a dual purpose strategy: "Look how qualified I am to be president, and by the way, it's also why I'm qualified to be vice-president."

Of course, Clinton is not just taking the dodge ball "choose me! choose me!" strategy of vice president selection.  She knows that if she keeps the race close, the Democratic power base will put pressure on Obama to choose her.  All she has to do is make nice in a plausible way before the race is over.  

This is where Penn comes in: he is the bad cop to Garin's good cop.  Clinton can plausibly blame the negative campaigning on Penn, and even though the Obama people won't completely buy it, it will be enough to let them justify a shared ticket.

We already see this narrative shaping up.  The Clinton campaign has let it be known that Mark Penn wanted to go even more negative against Obama with the 3 a.m. ad, but the noble Hillary and her good campaign members fought the good fight and kept the ad from being worse.

Expect more revelations like this in the near future.  Expect more praise of Obama from Hillary.  Expect more moments of mutual admiration and respect, like that moment in a past debate when Hillary said it was an honor to share the stage with Barack.

And this can be no scheming plot on Hillary's part.  I'd suspect that Obama is in on it.  There may have already been some back room conversations between the candidates and the DNC on how this should all go down.

It may even be the case that it's all been planned out by Mark Penn.