A new Washington Post/ABC News poll released this morning found that Hillary Clinton’s unfavorable rating has jumped to 53 percent — her highest in Post/ABC polling since 2008. Other polls have shown similar findings of late, and the usual suspects have been very quick to declare that this must show she’s sinking under the weight of the ongoing email story, which the public must care about very deeply.

But while there’s little question that the email story does matter, it may be only a part of a larger, more compelling explanation: Clinton does better in the polls when she is not seen as a partisan political figure, and she sinks in the polls when she is seen as a partisan political figure.

In other words, her drop was probably inevitable once she made the transition from Secretary of State — a job that carries the trappings of above-politics statesmanship, or if you prefer, states-womanship — to candidate for president.

As it turns out, this pattern has been visible in polling of Clinton that goes back over two decades. Scott Clement, one of the Post’s crack polling gurus, whipped up this chart of Clinton’s favorable ratings in national Post polling going all the way back to before 1992, when Hillary’s husband first won the presidency:

Run your cursor over the chart to get the details. As you can see, the pattern is pretty clear. After Bill Clinton won the presidency, Hillary Clinton’s national favorability rating jumped to 59 percent. It dropped during the 1994 midterm elections, and dropped precipitously, into the 20s and 30s, during the 1996 reelection campaign. It then climbed again, and reached a high point in the late 1990s, during the impeachment of Bill Clinton, when she became a sympathetic First Lady figure suffering the slings and arrows of politics.

Then, in 1999, when it became clear that Clinton was going to run for Senate from New York, her numbers sank down into the 50s and even into the 40s, where they remained throughout her victorious campaign. Her numbers then slowly climbed over the years, getting into the high 50s, then promptly sank just after she launched her last presidential campaign in early 2007. They jumped again, then dropped further towards the end of the losing 2008 presidential effort. They then rose again over the years as she carried out the job of Secretary of State, peaking in January of 2013 — before plummeting steadily as it became increasingly clear she was running for president again, to where they are now that she’s a declared candidate.

Now, obviously, it’s hard to know how important the cycling in and out of political roles has been in determining her numbers. There may have been other, different, transitory factors that influenced them over the years. But it’s worth noting that the political science bears out the idea that her changing roles might be a key factor.

“The political science would say that people assess Clinton based on the information they’re given,” John Sides, a George Washington University political science professor who founded the Post’s Monkey Cage blog, tells me. “When she moves out of electoral politics, she’s still at some remove from the day-to-day hullabaloo. When Clinton enters into electoral politics, she gets criticized by the opposing party and scrutinized by the media. The information voters get is less consistently positive, and as a consequence, people’s assessments change.”

“What you’ve seen since she announced for president is exactly that process play out,” Sides continues. “It’s driven by Republicans, but also by the scrutiny she gets as a candidate.” Nate Silver has also observed this pattern play out with Clinton over the years.

What’s more, Clinton may occupy a bit of a unique position as someone — as a woman — who has consistently cycled back and forth from non-political, above-the-fray roles that nonetheless attract enormous national media scrutiny (First Lady, Secretary of State), to equally high-profile political roles (Senate candidate, presidential candidate, and, now, presidential candidate again).

Howard Wolfson, who was a high level strategist on both Clinton’s 2000 Senate campaign and her 2008 presidential campaign, has been uniquely positioned to observe this dynamic, which he’s seen play out repeatedly.

“In 1999, she began the campaign as First Lady,” Wolfson tells me. “As she became a political figure and a target of attacks, her numbers reflected that. This dynamic is not all that dissimilar from the current one. She was out of politics as Secretary of State, and now that she’s re-entered the political arena, she’s become a more political figure by definition. And her numbers now reflect that.”

None of this is to say that the email story isn’t taking a toll on her image. Polls show majorities see her handling of her emails as problematic, and the story probably does feed into a longtime vulnerability of hers — questions about her honesty. But the point is that a drop in her numbers was probably inevitable. Even if the email story is in fact exacerbating her current troubles, it is probably just feeding into a dynamic that might have been there anyway.

If there had been no email story, voters would probably be getting fed other types of negative information, due to attacks from the opposition party and intensified scrutiny from the political media. And at any rate, Clinton’s career appears to illustrate — perhaps to a unique degree — that the American people have consistently been much tougher on her when she’s a politician than when she isn’t.

In other words, if you look back at the big picture, none of what we’re seeing now is all that surprising.