"As soon as it's midnight at the end of a quarter, then the only thing to start worrying about is that we're now in a new quarter," Box CEO Aaron Levie said on a recent episode of the SaaStr podcast. "Especially in software businesses that are in hyper-competitive markets, if you're not focused on the future at all times you're gonna lose. You don't have a lot of time to stand around and celebrate."

The reaction to Box's year-end earnings report shows just why that's so. If there were a time to "stand around and celebrate," the end of Q4 would be a pretty good one for Levie's enterprise could storage company. Revenue grew almost 30 percent year-over-year, and deferred revenue grew exactly 30 percent. (Incidentally, that's pretty close to the growth numbers posted by SaaS giant Salesforce.) The company has 71,000 paying customers, including 64 percent of the Fortune 500.

Perhaps most impressively, Box is finally free cash flow positive, making good on a promise Levie made to Wall Street in 2016. The company intends to carry that forward during the 2018 fiscal year. "We don't need to raise any more capital in the market -- we are self-sufficient," Levie told CNBC. The company expects annual revenue to hit or exceed $500 million in 2018.

So why is the share price down $2 after their earnings call? $BOX closed at a record high, but quickly lost the 3 percent gain when the markets opened again. MarketWatch noted that "Box reported a net loss of $36.9 million, or 28 cents a share, on revenue of $109.9 million, as well as billings -- an important metric in cloud software that represents contracts for future revenue -- of $159.3 million." The company updated its fiscal-year forecast to show losses somewhat larger than Wall Street analysts had expected.

A potential concern is Box's pipeline reliance on IBM in an era where the latter company's revenue numbers are constantly lagging. "IBM contributed to our record pipeline earlier in the year," Box CEO Aaron Levie explained on the earnings call. "And in Q4, that effort resulted in IBM being part of as 18 of our 64 deals above $100,000. We also continue to deepen our product partnership with IBM."

On the other hand, Levie did indicate that Box will bulk up its sales and marketing capabilities; the company is probably aware that partnership dependencies have downsides even when they're currently bringing in business.

As it stands, Box's path toward growth depends heavily on its existing customers. CFO Dylan Smith told Canaccord analyst Richard Davis, "In terms of the breakdown of the new bookings that we've been driving [...] two-thirds [are] coming from existing customers and that's a combination of additional seats and additional products, and then about a third of those new bookings [are] coming from customers buying Box for the first time." Smith said that Box is "just over 7 percent penetrated in the Fortune 500 companies where we do have paying deployment."

This could be interpreted as a promising sign, since Box is demonstrating enough value for current customers to want to expand their usage -- or as a bad sign, because they're not conquering greenfield in the way they used to. Granted, the proportion of the Fortune 500 currently signed on with Box is roughly equivalent to the proportion of their new bookings that come from existing customers. Those two figures could be related.

On the product side, Box wants to make sure investors and potential customers know that it's not just a file-storage company. Box is executing the play for enterprise content-management that Dropbox was never able to, including sophisticated permissions and compliance features that are crucial to any large, regulated organization. Think finance -- including banking and insurance -- healthcare, and government itself.

As Levie said on the earnings call, Box is riding the wave of "a multi-year secular shift from legacy enterprise content management solutions and storage technology in the on-premises environment to the cloud." Levie continued, "We believe we're best positioned to be able to take advantage of that migration."