So why did investors pummel its shares by more than 5% the day after the earnings were annouced, erasing $25 billion in market cap, and driving Apple’s price-to-earnings multiple into the single-digits?

Put simply, the analysts, fund managers, and everyday shareholders who were once fervent believers now fear Apple’s spectacular run just ended. Apple’s forecast for its fiscal second quarter underscored those fears. For the period ending in March, Apple predicts sales of between $50 and $53 billion, a big drop from the $58 billion logged for the same period in 2015. With its trademark transparency, Apple also included a breakdown of its major expenses for the current quarter.

Management didn’t provide an outlook for net earnings, but a rough figure is easy to estimate. Apple should earn around $10.8 billion in the March quarter. That’s 21% below its profits of $13.6 billion for the same period a year ago.

The impending slump in revenues and profits raises a crucial question for Apple’s shaken fans: What is the “new normal” for Apple’s future profitability, and does that new normal make Apple the terrific bargain that its lowly multiple seems to indicate?

Here’s something that has been forgotten recently: Apple’s profit history has always been erratic. The projections for the second quarter point to a return of the average earnings it’s shown over the past several years, as opposed to the huge spikes in recent quarters. It was the fantastically successful launch of the iPhone 6 that generated those record numbers. But Apple can no longer match the run of annualized earnings in the mid-$50 billion range. Apple’s pipeline lacks any blockbusters with iPhone-scale potential.

One reasonable way to calculate Apple’s future profitability is to average its trailing profits over the past dozen quarters, including the forecast for the March period. Its average annualized earnings over those 36 months is around $45 billion. If that number really represents its core, bedrock profits, Apple may well be a buy; its adjusted P/E would stand at around 12, far below the S&P 500 average of about 18 (based on trailing profits).

But to generate strong returns, even at that seemingly tempting P/E, Apple needs to grow, not shrink, as appears to be happening today. In the past, it’s managed to generate tremendous gains in revenues and earnings with relatively light investments in research and development and capital expenditures—chiefly because folks flock to buy fresh installment of the iPhone that are relatively inexpensive to develop.

Relative to sales, Apple still spends a lot less on R&D and capex than a Microsoft or Intel. But what matters most is the trend, and Apple is already raising its expenditures in both categories at a rapid rate. In its first fiscal quarter for 2014, Apple’s R&D and capex totaled $3.3 billion or 5.7% of sales; in its most recent quarter, the figure was $6 billion, accounting for 7.9% of revenues, and the figure could jump to 12% in as revenues fall in the second quarter.

Look for those investments to ramp rapidly as Apple lavishes funds on new products. It will need them to reverse the looming drop in sales. Of course, Apple could also make acquisitions to recharge growth. In any event, what rightly bothers investors is that the future will be a radical departure from its fabled past. Apple’s strength has always been harnessing its creativity to squeeze big profits from smidgens of new capital. Those days are ending. Going forward, Apple will need to invest heavily like most of its rivals. It’s anything but certain that Apple will generate decent returns on all that new investment.

That was obvious before the believers cheered Apple’s run towards a trillion dollar valuation. Now, Apple fans are fewer, but it still has plenty of champions pitching it with a new rationale—as the ultimate value stock. Maybe. But good value stocks still need to grow, not shrink, and believe it or not, the greatest tech player of them all still has a lot to prove.