Like many political junkies, I’ve been spending far too much time looking at polls and trying to understand their implications. Can Donald Trump really win his party’s nomination? (Yes.) Can Bernie Sanders? (No.) But the primaries aren’t the only things being polled; we’re still getting updates on President Obama’s overall approval. And something striking has happened on that front.

At the end of 2015 Mr. Obama was still underwater, with significantly more Americans disapproving than approving. Since then, however, his approval has risen sharply while disapproval has plunged. He’s still only in modestly positive territory, but the net movement in polling averages has been about 11 percentage points, which is a lot.

What’s going on?

Well, one answer is that voters have lately been given a taste of what really bad leaders look like. But I’d like to think that the public is also starting to realize just how successful the Obama administration has been in addressing America’s problems. And there are lessons from that success for those willing to learn.

I know that it’s hard for many people on both sides to wrap their minds around the notion of Obama-as-success. On the left, those caught up in the enthusiasms of 2008 feel let down by the prosaic reality of governing in a deeply polarized political system. Meanwhile, conservative ideology predicts disaster from any attempt to tax the rich, help the less fortunate and rein in the excesses of the market; and what are you going to believe, the ideology or your own lying eyes?