After shipping more than Samsung with purely $600+ phones last holiday season, iPhones consistently outsell themselves YoY, locking up almost all the profits in phones, tablets and consumer PCs = Apple is underperforming, because.
Unrealistic investors should get a brutal kick to the genitals like they deserve.
If they were projected to do even better, they can still be under-performing.
Stock prices doesn't operate relative to how well a company is doing to everyone else, the operate based on expectations, regardless of how reasonable or unrealistic those expectations might be.
If you think the market is behaving irrationally with respect to Apple, you should clearly be able to make all kinds of money by investing your own money. If other investors are being unrealistic, you should be able to profit at their expense.