I agree with Matt Stoller's conclusions, although I take a different route to get there. Stoller is critical of the following three-part line of attack on John McCain, developed by James Vega at the The Democratic Strategist (.pdf):

McCain's actions in recent weeks have provided compelling evidence for three genuinely disturbing propositions about his character, core values and integrity.

1. That John McCain has become desperate to win this election and is willing to sacrifice his deepest principles and his personal honor in order to do it.
   
2. That the John McCain we see today is only a pale, diminished shadow of the
   man he once was in his early years.
   
3. That John McCain is allowing men he once despised and held in complete contempt to manipulate him and tell him what to do - to literally put words in his mouth and tell him what to say.

At first glance these statements are so strong that they sound almost defamatory. But each is supported by McCain's recent actions (as described below) and they fit together into a single coherent narrative of ambition overcoming integrity and moral character.

Frankly, only a beltway insider would come up with this kind of a list. First of all, the whole line of attack makes a completely unnecessary concession. It basically grants that up until relatively recently John McCain was a man with deep principles and personal honor. That's the exact myth the establishment media has been selling us on John McCain for years now, and it has never been true. Never.

In fairness to Vega, he may not believe it is true. He may simply judge that that angelic view of John McCain is so well-ingrained in the public's mind that it isn't worth trying to overwrite people's hard-drive memories. But it is this second point that is most assuredly wrong. The press likes John McCain and that clouds their objectivity. They see McCain snuggling up to the religious right, jettisoning any pretense of fiscal discipline, adopting a foreign policy stance to the right of Dick Cheney, and taking advice from Karl Rove and Rove's staff...and they are disappointed. Vega's line of attack is actually nothing more or less than what these disillusioned media-types are telling themselves to ease their cognitive dissonance. It couldn't be that all along John McCain was a dishonorable, ethically challenged, opportunistic, dishonest, unserious cad. That would mean that the media had been, well, had. No. No. It must be that John McCain has changed. He's not the man he used to be. He's become desperate and he's abandoning all these fine principles. This is all horseshit, plain and simple.

If the press is feeling let down by John McCain they should blame themselves for not paying close enough attention to the man over the years. On balance, McCain's recent moves are less a sign of desperation than they are that he is serious about winning. He has managed to make progress in the polls using these tactics. But, as Matt Stoller points out, the very strategies that poll well for Obama (attacking McCain over his age and age-related performance problems, over his temper, over his radicalism, over his unpopularity within his own caucus and inability to work well with others) are the issues that Vega dismisses.

The more difficult problem is that McCain is not, at first glance, an easy target for attacks on his character. His youthful military experience as a pilot and POW and his well-cultivated media reputation as an occasional "maverick" in the 80's and 90's present no obvious vulnerabilities. Current characterizations of him as old, ill-tempered, easily flustered and prone to blundering, while certainly true, are also essentially trivial. Comparing McCain to "The Simpsons'" Mr. Burns or to a clichéd grouchy grandpa simply has no meaningful political effect.

Karl Rove perfected the strategy of going right after a candidate's greatest strength. In Kerry's case it was his distinguished military record. In Obama's case it is his charisma and popularity abroad. In McCain's case it is his reputation as a maverick, his media-darling status, and his record as a Vietnam veteran and POW. Those are precisely the strengths that need to be taken on squarely. And there are more.

McCain is showing age-related performance problems. He's taking radical right positions on abortion, on foreign policy, on social security, and more. Many members of his caucus are profoundly discomfited by the very idea of John McCain as commander in chief.

Some of these chinks in McCain's armor are somewhat delicate subjects. It would not be seemly or politically savvy for Barack Obama to attack John McCain's age or military record. And, given how much McCain suffered as a POW, some of it should be off limits, even for surrogates. But McCain invites rebuttal when he makes up stories from his time as a POW. Regardless, John McCain graduated near the bottom of his class at the Naval Academy, trashed several planes (both before and after his captivity in Hanoi), and has misrepresented his reasons for retiring from the armed services. There is no reason that surrogates can't point that out.

John McCain admitted this week that his greatest moral failing was the break-up of his first marriage. What was so horrible about McCain's behavior in that marriage that is surpasses his vote against Martin Luther King Day, or his role in the Keating 5, or his decision to defend the flying of the Confederate Flag over the South Carolina capital?

And when we talk about age discrimination, we're typically talking about denying job opportunities to people in their forties, fifties, and sixties. Once you reach the age of 72 people no longer question the morality of using your age as a reason to deny you employment. If McCain serves two full terms, he'll be 80 years old before he leaves office. How many jobs can an 80-year-old expect to he hired on for? Over forty percent of the public say that they would not vote for someone that is 72-years-old. As Stoller points out, this is roughly the same percentage that would not vote for a homosexual. But, unlike with the issue of homosexuality, being wary of extreme old age is not mere prejudice. This is particularly true with a man that is showing demonstrative and repeated signs of age-related diminishment. Add to this, McCain's legendary temper and his Republican colleagues' clear ambivalence about his fitness for office, and you've got a potent and legitimate set of concerns to take to the public.

What are a few panders and flip-flops in comparison? The danger for Obama is that by listening to Beltway consultants and media insiders he may make the mistake of conceding that John McCain was once a man of honor, integrity, and principle. He wasn't honorable at the Naval Academy. He wasn't honorable in his first marriage. He wasn't honorable when he voted against MLK Day, or when he got involved in the Keating Five. He wasn't honorable when he defended the Confederate Flag (as he has admitted). He's not being honorable now. So, when was he honorable? There is only so much deference you can pay to a man's captivity at the hands of the NVA. How long are we going to let crap like this go without hitting back?

Nicolle Wallace, a spokeswoman for Mr. McCain, said on Sunday night that Mr. McCain had not heard the broadcast of the event [at Rick Warren's Saddleback Church] while in his motorcade and heard none of the questions.

“The insinuation from the Obama campaign that John McCain, a former prisoner of war, cheated is outrageous,” Ms. Wallace said.

I mean, seriously.