Hot on the heels of a very successful 2014, during which the company's major business units grew faster than expected, 2015 has been a bit of a downer for chip giant Intel (NASDAQ:INTC). The company expects its revenue to be down by 1% and current analyst estimates are looking for earnings per share to drop from $2.31 in the year prior to just $2.23 this year.

Commensurate with this small decline in revenue and earnings, Intel's shares are down a little over 2% year to date.

To get a better understanding of what drove both the company's financial results downward, here are some of the worst Intel headlines of the year.

Intel cuts quarterly, full year guidance
Intel didn't exactly start the year off well. After guiding to revenue of $13.7 billion (plus or minus $500 million) for the first quarter of the year, the company cut its guidance to just $12.8 million (plus or minus $300 million). This reduction was due to "weaker than expected demand for business desktop PCs and lower than expected inventories across the PC supply chain."

The weak demand, Intel said, was due to "lower than expected Windows XP refresh in small and medium businesses" as well as "increasingly challenging macroeconomic and currency conditions."

In the company's full earnings results that followed about a month later, the company took down its full year guidance from revenue growth in the mid-single digits to about flat to 2014 levels.

Another full-year guidance cut
When it came time for Intel to report results for its second quarter, the company's results were in line with prior guidance. Unfortunately, the company yet again took down its revenue guidance for the full year. Company CFO Stacy Smith said that PC inventories "declined at a slower rate" than the company had previously expected as PC demand weakened further.

10-nanometer manufacturing technology delay
In the same earnings call in which Intel lowered its full-year outlook, the company also announced something that came as a surprise to many: the ramp of its 10-nanometer manufacturing technology would be delayed by approximately a year as a result of what were strongly implied to be manufacturing yield challenges.

In the place of the 10-nanometer products that were supposed to launch in 2016, Intel disclosed that it would instead launch a processor family known as Kaby Lake built on the same 14-nanometer technology that it used to manufacture Broadwell and Skylake.

Although it is good that Intel will have a new processor family in 2016 (and won't instead try to get two years of life out of older chip designs), Intel would have been in an even stronger competitive position had it been able to deliver 10-nanometer product in 2016 than another 14-nanometer product.

Worse-than-expected data center results
Intel has made it clear that it expects its data center group to be its main growth engine going forward. During the company's investor meeting in late 2014, management guided to revenue growth in excess of 15% in this segment during 2015 with operating profit growth outpacing revenue growth.

Management stuck to this forecast through most of 2015, but during its third-quarter earnings call lowered its revenue growth forecast to "low-double-digit" percentage growth. Interestingly, revenue is up 13% in this segment year to date, with operating profit up just 11%, strongly suggesting that operating profit growth will trail revenue growth for the year.

Not a great year, but not terrible
2015 certainly wasn't a particularly good year for the company, as it missed the financial forecasts that it gave late last year across its major business units and is ultimately poised to see revenue and profit declines for the year.

That being said, I still think the longer-term story is intact: the company's data center business is still growing and all indications point to a PC market in 2016 that's flat-to-down relative to 2015 levels (which were quite low to begin with) -- much better than the large decline seen this year.

Ashraf Eassa owns shares of Intel. The Motley Fool recommends Intel. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.