In fact, "Emoji" did surpass the modest expectations held by both its studio (Sony) and box office experts. Most predicted a debut of around $20 million for the cartoon, yet it premiered with an estimated $2.7 million. Among new wide releases, "Emoji" beat Charlize Theron's spy thriller "Atomic Blonde," which underperformed slightly with an estimated $18.6 million and debuted in fourth place.

Even so, "Emoji" wasn't strong enough to overcome "Dunkirk," a week-old movie aimed at much older audiences, with no box office stars. The World War II drama finished first again with an estimated $28.1 million. Bad reviews and less-than-okay audience ratings lead to "Emoji" striking out. Here are a few more reasons:

"Dunkirk" has some of the year's best reviews (with a 93 percent fresh score from critics at Rotten Tomatoes) and audience word-of-mouth (an A- at CinemaScore). Critics also liked "Atomic Blonde" (75 percent at RT), but audiences were less thrilled (a B at CinemaScore).

Viewers gave "Emoji" a B, which is a very weak grade for a cartoon. And critics absolutely hated it (8 percent "Rotten"). A kid-appeal movie like "Emoji" ought to be critic-proof, but the CinemaScore grade indicates that paying customers were as disappointed as reviewers were. And Sony must have known critics wouldn't like it, since it withheld the film from them until the last minute. Hollywood has been complaining all summer that low scores on Rotten Tomatoes are hurting sales, but having no score at all doesn't necessarily help.

2. Audience
Kids' movies are not the automatic gold mine they once were. Look at this summer's "Diary of a Wimpy Kid: The Long Haul," which topped out at $20.7 million, or Sony's own recent "Smurfs: The Lost Village," whose $45.0 million domestic take is by far the lowest for the three "Smurfs" movies. The reason? Kids don't always make the ticket-buying decisions. Often, their parents do, and there was little about the film that appealed to grown-ups.

4. Timing
"Atomic Blonde" took some advantage of the girl-power trend, though it had to settle for sharing the female audience with "Girls Trip" and the action audience with "Dunkirk" and several other holdover hits. It might have done better had it opened a week or two later, or it might have struggled against Stephen King fantasy epic "The Dark Tower" and Halle Berry's "Kidnap."

"Emoji," however, benefited from being released a full month after the last major kids' cartoon, "Despicable Me 3," so it pretty much had the marketplace to itself.

As for "Emoji," many of the comedy-credentialed names in the voice cast (T.J. Miller, Maya Rudolph) don't matter to kids and won't necessarily impress adults. Casting a beloved Shakespearean thespian (Patrick Stewart) as the poop emoji isn't going to fool grown-ups into thinking "Emoji" is a prestige picture.

6. Social Media
Of course, "Emoji" was made to be marketed on your kids' phones. Sony partnered with numerous apps to release "Emoji"-branded content. And "Emoji" stars like Christina Aguilera and Sofia Vergara were able to leverage their large social media followings into interest in the movie.

To the extent that it takes eye-grabbing, immersive spectacle to draw moviegoers out of their living rooms and into the theaters, "Dunkirk" has a clear advantage.

Adults may not be as fluent as kids are in the language of emojis, but a blank space at RT the day before a movie opens is a sign that smart, ticket-buying moms know how to read.