David Gergen is a senior political analyst for CNN and has been a White House adviser to four presidents. A graduate of Harvard Law School, he is a professor of public service and co-director of the Center for Public Leadership at the Harvard Kennedy School. Follow him on Twitter: @david_gergen . The opinions expressed in this commentary are his.

(CNN) As they brace for harsh media attacks on their first 100 days, President Donald Trump's team points out with justification that other presidents have stumbled, too.

John Kennedy had a disaster with the Bay of Pigs invasion of Cuba. Bill Clinton slipped and fell in a controversy over gay people in the military. The George W. Bush team failed to pay sufficient attention to intelligence warning of terrorists hijacking airplanes.

As Richard Neustadt argued in a seminal book on presidential power, a new White House team must make some of their biggest decisions early on -- at a time when they are least experienced -- and mistakes happen.

Even so, events of the past few days underscore a sharp and potentially dangerous difference between the Trump administration and several of its predecessors: most others -- Kennedy and Clinton in particular -- were learning organizations that got much better on the job as they went.

By contrast, the performance of the Trump team suggests that its learning curve is a lot flatter than it should be. To be fair, there have been some encouraging signs of improvement, especially in international affairs where the arrival of Gen. H.R. McMaster as national security adviser has brought a crisper decision-making and execution process.

Even that, however, is not what it should be: the recent snafus over the whereabouts of an aircraft carrier group were surely embarrassing to a professional like McMaster. And the world is still scratching its head over what strategy and leadership role Trump is pursuing globally.

By this time in his presidency, there should be a sense that he and his team have a firm grip on governance. But on matters big and small, the administration in recent days has revealed that it is making many of the same kind of mistakes it made a few months ago:

Secrecy

From the beginning, an administration that promised transparency has engaged in excessive secrecy, feeding a narrative that it is trying to hide things. Why then would it put a new lid on its visitor logs? Why haven't they learned that doubling down may feel macho but it further erodes public trust.

New plan on health care?

From the beginning, there have also been worries in the press and public that the President is a con man, selling something that isn't what it seems. This isn't good for him or the country. Why then has the administration latched onto the new plan for health care reform coming out of the House Republicans? Under the plan, according to preliminary reports, the federal government would continue to provide many of the supports of Obamacare -- but would give states the right to strip them away. How can the sick and elderly rely upon such a scheme? Many of them will think it is a con job.

Taxing question

Similarly, Trump's Treasury Secretary and his top economic adviser in the White House have said in recent days that instead of paying for big tax cuts the old fashioned way -- by cutting spending or raising other taxes -- the White House may instead assume much faster economic growth, bringing in much more revenue.

Most mainstream economists are deeply skeptical that such big tax cuts will automatically produce dramatic gains in growth; indeed, the markets in recent days are suggesting that the economy -- initially boosted by Trump -- is already sliding back toward sub-normal growth. How long will it take before Democrats target Trump tax cuts as another con job benefiting him and his friends?

Disorder in the White House?

Even as polls show that Trump is holding onto his base support, they also show that the general public is tiring of his hype and wild gyrations. A more orderly White House is obviously needed. Why then, in recent days, has Trump insisted that Congress not only avert a government shutdown this coming week but also pass the health care bill in the House -- something no one on the Hill expects to happen?

Why in the world did Trump also surprise his Treasury Department by proclaiming that by Wednesday or shortly after, he will propose his tax plan? His own team is skeptical. Sorry folks, this isn't the way an orderly White House works.

Hosting Ted Nugent?

His White House staff has rightly said that time is a premium asset for the President. It may seem petty to raise the question of why then he reportedly still gives short shrift to national security briefings but this past week gave four hours to serving dinner and a guided tour to Sarah Palin, Kid Rock and Ted Nugent, the latter a notorious racist who has called for the hanging of Hillary Clinton and Barack Obama and called Obama a "subhuman mongrel."

White House advisers could well dismiss all this as so much cavil. Look, they could rightly say, he isn't tweeting quite so much and for the most part, his tweets have been less sulfurous. Yes, that's true -- and thank goodness -- but it is also missing the bigger point: that in so many ways, things haven't really improved that much.

The secrecy, the deception, the hype, the internal struggles, the slow-moving appointments process, the sliming of opponents, the lack of strategy, on and on -- all are pretty much the same.

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Other recent presidents have shown how important it is to learn and grow in office. After mishandling the Bay of Pigs, Kennedy bore down and a year and a half later was a magnificent leader in the Cuban missile crisis, averting a near nuclear war. Clinton pulled himself together after his early mistakes and became a much crisper, more effective president. With time, determination and self-reflection, Barack Obama became a much better president.

Not just for their sake but for the country's, it is important that Trump and his team now seize upon this 100-day landmark, stop being so defensive, and quietly learn from these early months how to govern effectively. History shows that it can be done.