It’s too bad that Comcast (CMCSA) CEO Brian Roberts waited until after the holidays to make the stunning announcement that the world’s largest cable company had gained video customers for the first time in six years in the fourth quarter.

If the news came any sooner, it would have been hailed as a Christmas miracle.

Roberts, whose father Ralph founded the company in 1963, offered few specifics about how it managed to pull off such a feat other than to say “It is a real beginning of an exciting reversal of trends.”

The fact that Roberts was so vague proves a few things, which should interest people who might want to buy CMCSA stock.

First, the macroeconomic trends remain tough, which means the customer gain probably isn’t very much. About 5 million people have quit cable television over the past five years. With the exception of hit shows like A&E’s Duck Dynasty and sports programming, ratings for many broadcast and cable channels continue to be stagnant. (But CMCSA stock investors are mostly aware of that already.)

Also, Comcast is widely bemoaned for its customer service woes, but many might not realize the lengths CMCSA goes to keep its customers from jumping ship to other cable or satellite providers — which might explain the company’s surprising success in its video business. I managed to get Comcast to shave $100 off my monthly triple play service bill just by asking. Comcast’s customer service line even has a number to push for people who are thinking of leaving the service.

Conversely, though, while Comcast convinced my wife and I to stay, it’s hard to imagine CMCSA will jump through an unlimited number of hoops every time a customer calls with a cord cutting story.

Nonetheless, Comcast investors — who have pushed CMCSA’ stock up 37% over the past year — are right to wonder how many deals like mine are being cut. That’s hard to say, but Comcast — whose average revenue per user (ARPU) is around $160 in the latest quarter — can afford to be generous because the infrastructure to serve its 50 million or so customers already exists.

On the other hand, pay television companies are in the same boat as wireless providers — the only possible way that they can grow is to steal another company’s customers. That means margins will remain under pressure for the foreseeable future.

CMCSA has loads of other challenges, most notably the growing numbers of people quitting cable television. But cord cutting, while not helpful, isn’t a full-out disaster for Comcast.

For one, many of these customers likely will continue to use CMCSA’s Internet service because … well, the content they want to view isn’t going to appear on its own.

Also, people need to put the issue of cord cutting in context. According to veteran cable industry analyst Craig Moffett, about 500,000 customers quit pay television service between July and December 2013. Magna Global estimates that cord cutting accounts for about 4% of TV homes today and may reach 11% over the next few years. Those numbers aren’t anything to scream about if you hold CMCSA stock … but they’re not devastating, either.

Part of the reason behind those relatively low numbers is that consumers (myself included) would rather deal with the devil they already know than take a chance on something that could be worse. Cord cutting takes many consumers out of their comfort zone, and inertia is a very powerful thing. That’s bad news for companies like Dish Network (DISH) and DirecTV (DTV), who are counting on customers jumping ship from CMCSA because of customer service or programming problems.

And with CMCSA adding customers, satellite companies are stuck in dire straits.

Bottom Line

Wall Street analysts act as if CMCSA and other cable companies can do no right, but enough people seem like to like the company. During the third quarter, almost 300,000 people signed up for Comcast’s combined video, high-speed Internet and television service.

Even so, people should hold off buying CMCSA stock at least until the company’s results are reported later this month (Jan. 18). The ARPU number is key because it will indicate whether Comcast is sacrificing profit to retain customers like me and to discourage people from cord cutting. If Comcast isn’t digging into itself too badly, there’s more reason to be optimistic about its video numbers.

And a little further down the road, all eyes will be on how many viewers tune into the Olympics on the company’s NBC broadcast and cable channels. Profiting from the Olympics has been a challenge for Comcast — CMCSA stock broke even on 2012’s London games, but lost money on the last Winter Games, held in 2010 in Vancouver.

As of this writing, Jonathan Berr did not hold a position in any of the aforementioned securities.