On Monday, Netflix shares dropped 89 cents, about six-tenths of a percentage point, to close at $146.92. That’s still close to their all-time high of $148.29, so at first glance the down day seems like the slightest of blips. Yet the reason behind the decline may be enough to give investors and TV industry observers pause heading into the company’s April 17 earnings announcement.William Power, an analyst with Baird who already maintains a neutral rating on Netflix, issued a report Monday based on the firm’s quarterly survey of U.S. subscribers. The results make him “cautious” heading into the quarterly release, he wrote,"Though the quarter included several solid new shows, it seemed to lack a strong universal new hit.”Earlier periods have featured the must-see likes of "Making a Murderer," "Stranger Things" or the O.G. tandem of originals, "House of Cards" and "Orange is the New Black." About 51% of respondents to the Baird survey said they were Netflix subscribers, which is flat from the fourth quarter. In prior years, there has been a double-digit increase from the fourth quarter to the first.Let’s acknowledge up front that the conclusions drawn from these data points are not unassailable. The Baird subscriber number, already a rough estimate, appears to be flat because of a perceived lack of a top-drawer title. Can that be proven unequivocally? It cannot.Unlike other TV programmers, there are no ratings, aftermarket sales or other metrics on which the performance of a show can be judged. There is only the number of subscribers. If that continues going up, which it did dramatically in the fourth quarter to push the company to more than 93 million worldwide subscribers, all will be right in the capital city of Streamville.If it doesn't keep rising, though, at least domestically — and several factors do suggest the laws of gravity will eventually come into play for Netflix — it will be a delicate moment in the company’s remarkable run.When Netflix content chief Ted Sarandos met the media at the TCA summer press tour last July, he reiterated the company’s emphasis on subscriptions. “Ratings and reporting on ratings are an important part of the industry,” he said. “But the focus of ratings has no importance to us.” He also noted that the company’s shock-and-awe spending of some $6 billion a year on content, increasingly originals, was designed to lift the overall quality level. “There are too many mediocre, safe shows,” he said of the general landscape.Here’s the issue, though: The amount of money being spent has certainly banished mediocrity, but it simply must move the needle in terms of subscriptions. Unlike broadcast and cable networks, which increasingly play to the middle and manage to keep charging advertisers higher rates for diminishing shares of the market, Netflix and other streaming services are held to their own, different standards. They also cannot raise rates, unlike their linear competitors. When Netflix did so, in 2016, subscription rates faltered.So then, what exactly defines a Netflix hit? Some measurement companies, notably Symphony Advanced Media and Parrot Analytics, have tried to definitively track how many views Netflix content gets. But critical reception, awards heat and cultural buzz are major parts of the mix. And recent months have yielded lackluster shows like Marvel’s "Iron Fist" or Baz Luhrmann’s ham-fisted hip-hop origin story "The Get Down."Both have been renewed despite feeble Metacritic scores (37% for "Iron Fist," 69% for "The Get Down") and non-existent buzz. But the original content narrative has been controlled by FX of late, with "The Americans," "Feud" and the soon-to-return "Fargo," or traditional premium networks like HBO and Showtime with "Westworld," "Big Little Lies" and "Billions," respectively.When HBO's Sunday night dominance with "The Sopranos" and "Sex and the City" was being challenged by ABC's "Desperate Housewives" in 2005, then-network chief Chris Albrecht told the New York Times, "we can’t get distracted by somebody else’s rules or scorecard."The same applies to streaming services today. Netflix has made a ton of high-quality programming across the gamut, from comedy to drama, documentary features to unscripted series. But just like the networks still judged by outdated metrics like Nielsen ratings, capturing what will compel people to subscribe is Netflix’s alpha and omega.No matter how many billions they have, money doesn’t equal mastery of the zeitgeist. Having the service at all, with its clean, intuitive interface, used to be such an invigorating novelty that people would subscribe just for that experience alone. Now, with penetration arguably nearing peak levels Stateside, it’s increasingly about whether the shows compel people to subscribe. Must they subscribe? Even though Sarandos and his team correctly remind Wall Street and the media of the game they are playing, they still have to step up to the plate.