Editor's note: A previous version of this article misidentified David Einhorn of Greenlight Capital. The Fool regrets the error.

Microsoft (Nasdaq: MSFT) hasn't been getting a whole lot of love from investors in recent years, and now its fiery CEO is under fire.

Greenlight Capital's David Einhorn took jabs at Steve Ballmer during yesterday's Ira Sohn Conference, as retold by The New York Times' DealBook blog.

The match-lighting hedge fund manager believes that it's time for Ballmer to give someone else a shot at running the world's largest software company. He took Microsoft's helmsman to task for being out of touch with emerging trends and squandering the cash-rich company's money on ill-advised acquisitions.

Ballmer's an easy target these days. He's been at the helm throughout Microsoft's lost decade, a time that has seen Apple (Nasdaq: AAPL) shares appreciate several times over.

Einhorn criticizes Ballmer for what he has done -- including taking on Google (Nasdaq: GOOG) in search through Bing -- and what it has failed to do, by letting Apple corner the tablet and portable media player markets.

I don't think Ballmer is the problem, and anyone that has read what I have to say about Mr. Softy over the years knows that I am no bull on Microsoft.

In a nutshell, Microsoft will never be the company it used to be -- but that fate doesn't owe to anything that Ballmer did, or that anyone could have done differently. Microsoft will never be great again because potentially irreversible market trends are working against its bread-and-butter business.

Google has found ways to popularize free operating systems for mobile, tablets, and now computers, and it's attacking Microsoft's Office stronghold with free cloud-based productivity software. Every passing year will make Microsoft less able compete with its premium Windows and Office programs. Is that Ballmer's fault? I think Ballmer actually deserves credit for growing Microsoft's revenue, despite the heavy headwinds blowing into Redmond.

Did Microsoft's Zune come too late to challenge Apple's iPod? Yes, but what about companies including SanDisk (Nasdaq: SNDK) and Creative, which got their earlier and still failed to challenge Apple? Microsoft's Surface and Hewlett-Packard's (NYSE: HPQ) TouchSmart were ahead of their time before Apple popularized touchscreen computing with the iPad last year.

Apple is the world's most valuable tech company for a reason. You could ask every lesser company why it can't be more like Apple, but posing that questions doesn't mean that those businesses should can their CEOs.

Ballmer's trying, as you can see in the deals and acquisitions that have left Einhorn and others like him shaking their heads.

I actually applaud Ballmer for digging deep into Microsoft's coffers to get Yahoo! (Nasdaq: YHOO) to back Bing, and Nokia (NYSE: NOK) to back Windows Phone 7. Bing is now a legitimate -- and undisputed -- silver medalist in search. Having the world's leading handset maker championing its smartphone operating system can also only help it in this uphill battle.

It's easy to criticize Ballmer, but what would any other CEO have done differently? Microsoft doesn't need a new CEO to woo back investors. It needs a time machine. Last I checked, even Apple isn't working on one of those.

Is it time for Steve Ballmer to go? Share your tips in the comment box below.

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Longtime Fool contributor Rick Munarriz still does most of his computing via Microsoft's wares. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.