Since Nike (NYSE:NKE) became a member of the Dow Jones Industrial Average almost exactly a year ago, shares of the footwear and athletic apparel behemoth have climbed more than 18%.

But its impressive rise certainly hasn't been a straight march upward. Instead, patient investors in the $70 billion company have had to weather some surprisingly large drops and pops along the way, especially compared with the more steady climb of The Dow Jones Industrial Average of which it is now a component:

NKE Chart

NKE data by YCharts

So with shares currently trading near 52-week-highs, could Nike's shares possibly be a buy now?

I think so -- but only for investors who can maintain a proper long-term mind-set. Here's why.

Nike stock isn't cheap, but ...
To be sure, Nike stock looks expensive trading around 27 times trailing-12-month earnings, and nearly 21 times next year's estimates. Make no mistake -- that's a hefty premium to pay as analysts expect earnings to grow by less than 12% annually over the next five years. If Nike doesn't live up to Wall Street's expectations in any given quarter, that high valuation could come back to bite it.

Then again, that's also much "cheaper" than, say, Under Armour (NYSE:UAA), which commands a smaller $15 billion market cap, but whose shares currently sit at a jaw-dropping 90 and 57 times trailing earnings and next year's estimates, respectively.Of course, I'm also convinced Under Armour has plenty to offer long-term investors as well with its own outsized growth, early international expansion efforts, and fast-growing footwear business -- all of which are significant threats to Nike's slower-growing global empire.  

But that also doesn't mean both companies can't survive and thrive over the long term. In fact, we can't ignore that Nike already enjoys a massive head-start in nearly every geographic market that matters. Nike generated more than half its revenue overseas last quarter, compared with roughly 8% for Under Armour, so there's little debating who's the undisputed footwear and apparel champion of the world. As Nike continues to methodically expand its global presence -- especially in emerging markets whose fast-growing middle classes enjoy more disposable income -- you can bet it won't give up its market share without a fight.

Nike is focused on growing where it counts
And remember, despite Nike's already-enormous size, its fiscal 2014 revenue still rose 10% to $27.8 billion, which translated to 11% growth in earnings per diluted share. Last quarter, Nike told investors worldwide futures orders were up 11% (12% excluding currency changes) -- a testament to CEO Mark Parker's assertion that "there is absolutely no shortage of growth opportunities for Nike." 

Nike's direct-to-consumer business is performing well.

In addition, Nike achieved that result despite both currency headwinds and tepid growth in China, a country of more than 1.3 billion citizens that represented less than 10% of total sales last quarter. To combat the sluggish region, Nike underwent a business reset in China, which management says is finally showing signs of bearing fruit and should set the stage for years of sustained growth going forward. 

But even as it stood at the end its most recent fiscal year back on May 31, Nike had still managed to generate an impressive $2.1 billion in free cash flow, returned $3.4 billion to shareholders through share repurchases, and paid a $0.24-per-share quarterly dividend all the while.

What's more, Nike's selling, general, and administrative expenses last quarter looked abnormally high thanks mostly to "demand creation" investments behind the World Cup. Over the long term, those investments should serve to bolster Nike's status with global consumers.

Nike is also investing heavily in its high-margin direct-to-consumer business, sales from which climbed 22% for the year to exceed $5 billion for the first time. To put that achievement into perspective, Under Armour's latest guidance calls for its overall fiscal 2014 revenue to climb at most 29% to $3 billion.

Foolish takeaway
Nike's global business has many moving parts, which can possibly mean more things to break along the way. But if all the pieces fall into place -- from Nike's business reset in China, demand creation investments, increasing capital returns to shareholders, and sustained growth from its high-margin DTC business -- I think patient, long-term investors will be more than satisfied with their returns.

Steve Symington owns shares of Apple and Under Armour. The Motley Fool recommends and owns shares of Apple, Nike, and Under Armour. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.