One of the reasons Apple's stock has gotten clobbered lately is that many people think Apple has lost its edge in its most important product line: smartphones.

The iPhone has been such a mind-boggling success that it drives more than half of Apple's overall profit. And for most of the past five years, Apple has had a lock on the "best smartphone in the market."

In recent years, however, competitors have caught up with the iPhone. Some reviewers think Samsung's new phone is superior to Apple's latest phone. And many people expect Samsung to leap ahead when the new Galaxy S4 comes out this spring.

Another respected product reviewer, Consumer Reports, agrees with those who think Apple has lost its edge.

In fact, Consumer Reports' conclusion is even more depressing for Apple fans.

Consumer Reports actually rates the iPhone 5 the worst of the top smartphones.

CR doesn't spell out the reasoning for its numerical ratings (yet), but the results are still startling.

Below is the summary box of CR's lab tests, which appears in the February issue of the magazine. The numerical ratings are close together, but they're unequivocal.

As you can see, on AT&T and Sprint, the iPhone 5 is rated behind two phones:

* The LG Optimus G (Android) [The what?]

* The Samsung Galaxy S III (Android)

On Verizon, meanwhile, the iPhone 5 is rated beneath at least three smartphones:

* The Motorola Droid Razr Maxx (Android, and owned by Google)

* The Motorola Droid Razr HD (Android, and owned by Google)

* The Samsung Galaxy S III (Android)

Consumer Reports

Not even ranked in the top 3 at Verizon? Ranked behind Google phones in addition to Samsung phones? That must feel like a bit of a slap in the face.

Apple had better be cranking on the iPhone 6...

SEE ALSO: Why Apple Stock Is Getting Clobbered