Americans love rankings. There’s David Letterman’s “Top 10” list, of course. You can hardly surf the Web without stumbling across lists of best this and most that. “We’re number one!” is practically the national slogan, and being number one is fairly meaningless without a number two—and preferably a whole lot of other numbers against whom we can measure.

I know of what I speak: in my day job I am an editor and columnist at U.S. News & World Report, one of the founding fathers of the modern rankings-industrial complex. Our ubiquitous “Best Colleges” ranking has long since spawned a host of similar efforts—for high schools, law firms, hospitals, and grad schools—many of which have been imitated elsewhere. There is, so far as I know, no truth to the rumor that we’re about to launch “best rankings.”

It’s no surprise, then, that one of the enduring pastimes of political junkies and casual politicos alike is ranking the nation’s 44 chief executives. Here too I have some tangential connection: in 1948 my grandfather, the historian Arthur M. Schlesinger Sr., conducted a landmark poll of 55 historians for Life aiming to put our chief executives in a definitive order. It was a polling exercise that would be repeated at least a half-dozen times over the subsequent six decades. That half dozen included Grandpa himself conducting a second poll in 1962, and his son, my father, Arthur Jr., running one in 1996.

These seven surveys of historians and other scholars of the presidency are the basis and inspiration for Robert W. Merry’s new volume, Where They Stand. Taking the historians’ evaluations in tandem with the assessments of the voters, Merry displays an admirable instinct toward crowdsourcing in his exploration of presidential greatness and failure. “I place stock in collective assessments—the rankings of hundreds of historians through multiple surveys over several decades; and the collective judgment of the electorate as it hired and fired presidents through the course of American history,” he writes.

Of course, there are some problems with holding historians’ assessments in contrast with contemporaneous voters’. One small one is that it presumes that historians ignore voters’ judgments in their ratings. Some may, some may not. But it’s hard to say with certainty that the views of voters are heretofore unaccounted for.

A broader problem stems from the assumption underpinning Merry’s faith in the collective wisdom of the voters: that presidential elections are essentially referenda. He subscribes to the “13 keys” theory of the presidency proffered by historian Allan J. Lichtman and journalist Ken DeCell. In short, the idea is that there are a baker’s dozen of factors, ranging from the state of the economy to a third-party challenge to the incumbent’s charisma, that add up to predict which party will win the White House. If six or more of the “keys” turn against the incumbent party, it is doomed, but if the figure is five or less, it cannot be beaten. The system reportedly accounts for every presidential election, including correctly forecasting the last seven outcomes in a row. (In case you’re wondering, as I was, both Merry in an article last December and Lichtmann in an interview this spring counted only three keys turned against Obama.)

Merry sees this theory as superior to the “horse-race” approach dominant in today’s political journalism, which obsesses over every last tactical tic. There is much to be said for escaping the minute-by-minute hyperscrutiny of today’s political journalism. I’ve long argued that it is as if football games only unfolded one play per day, followed by 24 hours of analysis of why the coach called that play, whether the quarterback should be benched because his most recent pass was errant, and so forth. But there’s a danger in going too far in the other direction, forgetting that the players matter, and thinking games need not be played at all because of the infallibility of advanced statistics.

In the case of the Lichtman-DeCell keys, while one of them asks whether the challenger is a national hero or charismatic figure, they boil down to the notion of a presidential election as referendum, with the outcome being an implacable historical inevitability.

But a review of the modern presidency calls this into question. Was John F. Kennedy (or any generic Democrat) a shoo-in against Richard Nixon in 1960, or was the outcome plausibly affected by—take your pick—Nixon’s five o’clock shadow, Kennedy’s vigor, or the alleged depredations of Lyndon Johnson’s Texas political machine? Might the outcome of the 2000 race have been different if Florida had a simpler presidential ballot? Was George W. Bush invincible in 2004, or was he a vulnerable incumbent with the good fortune to face an especially feeble opponent?

And is it coincidence that the two modern incumbents who lost re-election—Jimmy Carter and George H.W. Bush, Gerald Ford never having been elected in the first place—fell to pols with exceptional political skills, Ronald Reagan and Bill Clinton? National context and historical trends matter, but so do candidates.

Having set up the tension between the historians and the mass assessments of the voters, Merry allots himself the role of arbiter. And certainly he is not unqualified. He is a veteran journalist and past editor of Congressional Quarterly and now runs The National Interest. He is widely read in American history, and he gives an engaging tour d’horizon of our presidents. He is most sure-footed when dealing with the undisputed greats, or “Men of Destiny” as Merry refers to them—George Washington, Thomas Jefferson, Andrew Jackson, Abraham Lincoln, Teddy Roosevelt, Franklin Roosevelt.

But the transition from being dubious of individualized analysis to providing it can be jarring. “Though I remain skeptical of individual judgments in rating presidents, including my own, I offer a few thoughts,” he writes at one point. In fact, he offers many thoughts. John Adams’s “elevated station in the historians’ polls may be a little too favorable.” Warren Harding’s historical standing (almost always dead last) “doesn’t make much sense,” and Calvin Coolidge “seems underrated by the historians,” while the “historians have gifted Hoover with remarkably high ratings.” Millard Fillmore “probably deserves better than the historians’ rankings,” while U.S. Grant’s most recent standing, 29th, is “about right.” And he has a special contempt for Woodrow Wilson, who “if there is justice (though in this instance there probably isn’t)” would reside on the list of worst presidents, in Merry’s view.

None of this is to suggest that Merry arrives at these conclusions out of the blue. He carefully makes his cases. Sometimes his arguments are compelling, and sometimes they are overdrawn, as when he compares President Obama’s Affordable Care Act with the 1854 Kansas-Nebraska Act, which repealed the 1820 Missouri Compromise, leading to the violence of “Bleeding Kansas,” a grim prelude to the Civil War. Such statements reflect Merry’s rightward lean.

And while he strives for something akin to a scientific approach, categorizing presidents according to how voters treated them (whether they were expelled after a single term, served two terms, or won re-election and were succeeded by someone from their own party), it is hard to assess greatness, especially in recent residents of the White House, without ideology. It is a concept that carries with it approval. Consider the case of Ronald Reagan. Merry believes the Gipper belongs in the “Leader of Destiny” category, while acknowledging that it is still too early to pass final judgment on him (and his successors). Was Reagan a great president in the sense of effectiveness? Undoubtedly. But was he great for the country? That remains a topic of hot debate.

And it will remain such for some while, even after history has had the space to give Reagan and his legacy their due, one way or the other. In the meantime, the great presidential ratings game goes on.

Robert Schlesinger is managing editor for opinion at U.S. News and World Report and the author of White House Ghosts: Presidents and Their Speechwriters.