The fall box office season wasn't supposed to kick into gear until next week. No one expected much from either "The Visit" or "The Perfect Guy," two low-budget films with little or no star power that opened this weekend. Maybe both films would open around $17 or $18 million, with a slight edge going to M. Night Shyamalan's horror movie "The Visit" because it was opening on 850 more screens than its rival.

Instead, both movies opened big -- about $10 million above expectations. And romance/thriller "The Perfect Guy" edged out "The Visit" by about $1 million, with estimates placing its debut at $26.7 million to "The Visit's" $25.7 million. After several weeks of dog-days doldrums at the box office, we finally have a real surge in sales at the multiplex.

What happened? How were the pundits all caught off guard? Here are some possible answers.

African-American Audiences Are Underserved

This should be obvious, and yet it's not. It's well-known that black viewers don't see their experience reflected often in mainstream Hollywood movies, which still feature predominantly white casts. So when we get a mini-wave of movies with black casts -- summer sleeper "Straight Outta Compton," religious drama "The War Room," and now, "The Perfect Guy" -- is it any wonder that black viewers come out in droves to see these films?

There's Star Power, and Then There's Star Power

"Perfect Guy" leads Sanaa Lathan, Michael Ealy, and Morris Chestnut may not be household names among all viewers, but African-American audiences know them well -- Lathan and Chestnut from the "Best Man" movies and Ealy from the "Think Like a Man" series. So the movie did benefit from their unique brand of star power.

So did "The Visit," but not from its actors. Rather, the star of "The Visit" is director Shyamalan, whose early spooky hits like "The Sixth Sense" and "Signs" made him a brand name and a one-man genre. Granted, that was a long time ago, and Shyamalan all but trashed his own brand with big flops like "The Happening," "The Last Airbender," and "After Earth."

Critics have seen "The Visit" as a return to the sort of modest, atmospheric, kid-centered horror that was his forte, but those hits were so long ago (from 1999 through 2004) that pundits weren't sure whether viewers remembered them better than his recent duds. Turns out they did, and that the Shyamalan brand still does have some drawing power, as long as he's making his old-school horror and not elaborate sci-fi/fantasy spectacle.

The Studio Touch

The other secret weapon behind "The Visit" was likely its distributor, Universal, which has dominated the box office this year like no studio since Disney in 1999 (which, by the way, was the year that Disney released "The Sixth Sense"). Big Hollywood studios don't always do well with small-scale movies ("The Visit" was made for just $5 million), but Universal correctly recognized that the film could succeed with a very wide release (nearly 3,100 screens) and proper marketing that emphasized Shyamalan's name and the rural-horror premise.

Don't shortchange Sony, though. The studio's ScreenGems label, which released "Perfect Guy," has a great deal of success with small-scale African-American films, including "The Wedding Ringer" and the "Think Like a Man" films. As a so-called specialty-films division, Screen Gems is well equipped to market low-budget films ("Perfect Guy" cost $12 million) while being backed with enough Sony muscle to book wide-release distribution, in this case, at more than 2,200 venues.

Other Underserved Audiences

"Perfect Guy" didn't just appeal to black viewers, but also to women in general (its plot about a successful woman whose new boyfriend turns out to be a dangerous creep is pretty universal) and to older viewers. Exit polling showed its audience to be 69 percent female and 58 percent over the age of 25. It may have swiped some of the potential ticket buyers for "The Visit," which, like most horror films, also skewed predominantly female 60 percent).

Rusty Box Office Tracking

As a group, the box office predictors have gotten it wrong a lot this summer -- arguably more than any other year -- with lowball predictions for a number of hit movies. In the case of "Jurassic World," they were off by tens of millions of dollars, and they didn't anticipate the successes of sleepers like "Compton" or "War Room." Are they still clinging to old assumptions about what sort of star power is still a box office draw these days, or the hunger of audiences other than teenage boys to see a wide variety of non-comic-book life experiences on the big screen?

If so, maybe surprise hits like "Perfect Guy" and "The Visit" can serve as a wake-up call.