If you want to pick a moment when Chris Christie’s star was at its brightest, the New Jersey governor’s first term had a wealth of choices. But I don’t think any of them topped the end of the question-and-answer session at his Reagan Library speech in the fall of 2011. This was Christie’s “moment.” And though that moment has passed, it’s instructive to recall its high point to understand the lessons that other candidates can learn about the timing of presidential campaigns.

The penultimate question asked of Christie–just to give a sense of how he was received out in California–was from a self-described “Jersey girl” whose family was back in the Garden State. “I just want to let you know that you make us so proud to be New Jerseyans and so proud to be Americans,” she said. And then she added: “And my Italian mother, she told me to tell you that you’ve got to run for president.” Christie joked that if she was so proud to be a New Jerseyan she ought to get back to Jersey to her family: “Getting more taxpayers, one at a time,” he said with a smile.

But the final question was from another woman in the audience, and here is what she said:

Governor Christie, all kidding aside. I’ve been listening to you tonight. You’re a very powerful and eloquent speaker. You know how to tell the American people what they need to hear. And I say this from the bottom of my heart, from my daughter who is right here and my grandchildren who are at home: I know New Jersey needs you, but I really implore you, I really do–this isn’t funny–I mean this with all my heart. We can’t wait another four years to 2016. And I really implore you, as a citizen of this country, please sir, to reconsider. Don’t even say anything tonight–of course you wouldn’t–go home and really think about it. Please. Do it for my daughter. Do it for our grandchildren. Do it for our sons. Please sir, we need you. Your country needs you to run for president.

Christie’s poll numbers were through the roof in his first term, and he even won the occasional Tea Party presidential straw poll. For 2012.

And that’s the point: in politics, as in much else, timing is everything. Christie’s moment was in 2012. It doesn’t matter if he didn’t feel ready at that time, and it’s admirable that he chose not to run when he believed he owed it to New Jersey to stay put. But that was the open door, and it’s closed now.

Even former supporters in Iowa, as the Associated Press reported a few days ago, are cool to Christie:

Four years ago, seven big-money donors and leading Republican activists from Iowa loaded into a private plane and headed to New Jersey for an urgent meeting with Chris Christie. Their message: Run, Chris, run.

The group from the lead-off caucus state failed in that mission to persuade the brash New Jersey governor to jump into the 2012 race for president. This time around, Christie’s White House ambitions no longer appear to be an issue. But those once-eager Iowans aren’t as keen to throw their support his way.

“It’s a brand new ballgame,” says donor Gary Kirke. “There’s a lot more people in the race, and a lot has happened since then.”

So what happened? Well, we had a scandal (Bridgegate), but that was after Christie’s reelection campaign ran head-smack into Hurricane Sandy. His embrace of President Obama on the eve of the 2012 election was emblematic of his falling out with conservatives, even as it was the foundation of his own reelection landslide. He still likely would have won without it, but the Christie mystique needed a big win to meet expectations, and his handling of the storm’s aftermath provided the fuel for just such a win. The reality of governing a very blue state as a Republican is not particularly conducive to also being a Tea Party hero.

Another aspect of Christie’s fall from conservative grace was the quality of the field in each election. In 2012, Christie was not the first “savior” that activists and donors thought might rescue the GOP from a bevy of weak candidates. There was also, among voters on the right, a sense of urgency in seeking to prevent a second Obama term. This time around, it’s an open seat. And the class of prospective candidates is strong.

But the key point is that we knew all this years ago. It was never going to be a surprise that stronger candidates would emerge in 2016, that Christie’s reelection campaign would have to tack to the center, that governing New Jersey requires a certain amount of cooperation with an overwhelmingly Democratic legislature, that Christie’s tough-guy approach was bound to find a more sympathetic target than public unions, or that style-centric flavors of the week are soon eclipsed by the next new thing.

That last one is something Barack Obama understood, to his credit. Could Obama’s career have survived losing in 2008 or passing on the race in a nod to Hillary’s “turn”? Sure. But at that point, he was nothing but a speech. And that speech would have been quite stale by the time 2016 rolled around. He wouldn’t have been the young, JFK-like smasher of the status quo. And his essential boringness, bitterness, and lack of knowledge of the issues would have been impossible to hide for another eight years.

2008 was Obama’s moment. 2012 was Christie’s. It doesn’t seem fair for Christie to be punished for his display of humility. But that’s presidential politics. Timing is everything.