Apple (NASDAQ:AAPL) enjoyed what could only be described as a phenomenal fiscal 2015, fueled by the runaway successes of the iPhone 6 and iPhone 6 Plus. With these devices, Apple finally tapped into the significant pent-up demand for larger-screen iPhones, driving meaningful revenue and market-share growth at the high end of the smartphone market and, ultimately, a solid boost in Apple's stock price.

However, after that excellent fiscal year, Apple seems to be getting fiscal 2016 off to a relatively underwhelming start. The company's financial guidance calls for modest year-over-year revenue growth from the same period in the prior year, but there have been several data points from Apple's supply chain to suggest that iPhone sales in the company's fiscal second quarter will see a year-over-year decline.

In my view, it is due to this widespread belief that iPhone sales will decline in the current fiscal year that Apple stock has plunged from its 52-week high of about $134 per share to about $105 as of a recent check -- a more than 20% haircut.

This has led some Apple investors to blame Apple CEO Tim Cook for the poor share price performance. However, I don't think that this is entirely fair.

What could Tim Cook have done differently?
The thing that I just don't really understand is just what some of the critics of Apple's management expect?

I have seen some arguments from frustrated investors saying that Apple's investor relations team should be more proactive in trying to "counter" some of the negative reports surrounding iPhone demand trends.

Do these investors realize that they're essentially asking Apple to update its guidance and/or issue guidance for the coming quarter while the quarter is still in progress? Maybe some investors would prefer if Apple offered mid-quarter updates like some major tech companies have historically done, or perhaps they would like monthly sales data, but frankly this an unreasonable request in this day and age.

Another complaint that I've seen from some investors is that Tim Cook doesn't do a good job painting a rosy picture of Apple's future to investors. Look, there's a reason that Apple only guides one quarter at a time: making predictions is really hard and getting it right one quarter at a time is tough enough.

Imagine if Apple issued full-year guidance at the beginning of the year but was forced to update it several times during the year? There aren't a whole lot of businesses in tech that can even reliably guide out a year at a time, so it would be borderline irresponsible for Tim Cook to come out and tell investors that everything is going to be great and wonderful over the next X years.

Of course, there are some that would like it if Apple were less "secretive" about its upcoming products, but this secrecy is done precisely to maximize shareholder value! Keeping things close to the vest helps Apple in two major ways.

The first is that it doesn't wind up subjecting its major product lines to the "Osborne Effect." Apple wants the customer to feel that the products it has in the market are worth buying and it would be silly for the company to tell customers about what it has in the pipeline.

Next, and perhaps more important, Apple doesn't want the competition to get wind of what it's working on, if that's at all possible. This means that whenever Apple introduces a novel feature or specification, the competition can't just catch up a month or two later. This helps Apple stay competitive in the marketplace.

Tim Cook is doing a fine job
I believe that Tim Cook is doing an excellent job running Apple. Although there are a few nitpicky things that I disagree with on the product side of things (for example, I think that using the same displays for two generations of iPhones in a row hurts the company's competitiveness during "s" product cycles), it's hard to find fault with how Cook and his team are running the company. 

Apple stock is suffering from the company's iPhone sales "coming back down to Earth" after seeing a massive iPhone 6/6 Plus cycle, plain and simple. 

Now, if Apple fails to grow iPhone sales during the coming iPhone 7 cycle, particularly since the year-over-year comparisons should be fairly easy to beat, then this could signal a problem with how Apple is running its business and ultimately an issue with Tim Cook's leadership.