Don’t crucify Facebook’s CFO — yet

May 24, 2012, 3:12 PM UTC

FORTUNE — David Ebersman’s career has been something of a fairy tale. Brown University, research analyst on Wall Street, and a stellar 15-year stint at Genentech, the world’s premier biotech company. By his mid-30s, he had emerged as a right-hand man to CEO Art Levinson, a Silicon Valley luminary, and his final act at Genentech was to negotiate the $46 billion sale of the company to Roche Holdings. Ebersman did all this while remaining an understated, behind-the-scenes guy who was always liked as much as he was respected.

But as Ebersman stepped into the public eye this month, the fairytale has quickly turned into a nightmare.

As Facebook’s (FB) chief financial officer, Ebersman, 42, was one of the lead puppeteers behind the company’s IPO, which is now being described as one of the most flawed debuts on Wall Street by a large company. It was Ebersman who authorized the underwriters to increase by 25% number of shares that would be sold to investors just days before the offering. And it was Ebersman who signed off on the $38 offering price, at the top of the range the company had announced it was considering. Combined, those decisions are largely being blamed for the precipitous 18% drop in Facebook’s stock price over two days this week.

MORE: Why LinkedIn fiddles as Facebook burns

What’s more, Ebersman — or someone on his team — is also said to have warned Wall Street analysts to lower their revenue forecasts, a warning that was not widely conveyed to individual investors. As a result, Ebersman has been named in a shareholder lawsuit against the company and its underwriters. For Ebersman, who spend most of the past year planning every last detail of Facebook’s mammoth IPO, this hardly counts as another notch in his storied resume.

But it is far too early to crucify Facebook’s CFO.

First, a good deal of the blame for the IPO debacle falls on NASDAQ, which suffered glitches, delays and was unable to deal effectively with a large number of cancellation orders for the stock, according to various reports. The glitches could have had a profound effect on market psychology, making many investors more skittish about buying the stock.

Second, while Ebersman’s team appears to have guided a select group of analysts about its revenue prospects, it is not clear that the guidance contradicted the information that Facebook provided in its prospectus, which outlined many areas of uncertainty and which specifically singled out concerns about its growth potential as users were shifting from the Web to mobile phones. A preliminary inquiry by the Securities and Exchange Commission is said to be looking at the issue of selective disclosure.

MORE: Who really won in Facebook’s IPO mess

Third, by some measures, Ebersman has done well by Facebook, and hence, by his shareholders (at least those who are in it for the long-term). Pricing an IPO stock is a mix of art and science. You have to gauge demand, something that is notoriously difficult in a case like Facebook’s, where a large number of individual investors who don’t typically participate in IPOs want in. And you have to balance competing goals: maximizing the amount of money that the company raises, while leaving some room for new investors to do well. Ebersman clearly achieved the former by pricing Facebook at $38; he utterly failed at the latter, at least in the short-term.

The one decision that Ebersman made that seems hard to justify is the call to increase the offering size. More shares being traded could help reduce volatility in the days following an IPO. But the additional shares were not sold by Facebook. Rather they were sold by early investors, a group that includes Peter Thiel, Accel Partners and Greylock Partners, Tiger Global Management and DST Global. They all got richer, but Facebook did not — and neither did the new holders of Facebook’s public shares. As my colleague Allan Sloan pointed out, enriching the well-connected at the expense of ordinary people hardly aligns with Facebook’s stated values.

That said, second-guessing Ebersman’s decision to price Facebook’s shares at $38 is a dicey proposition this close to the IPO.

Take LinkedIn (LNKD), which went public last year in an IPO that raised $353 million and was largely seen as successful. On its first day of trading, the stock more than doubled to $94.25. Since then, the shares have zigzagged up and down, but they never fell near the offering price of $45. And with the company on strong financial footing, LinkedIn shares are now trading at $103. Successful? It depends on who you are. Those who bought at the IPO did great. But it is clear that LinkedIn could have raised a lot more money without selling any more shares. By pricing at $45, it may have left as much as $300 million on the table, a sum that would boost its balance sheet by about a third and make the company even stronger.

MORE: Facebook IPO blunder adds to Morgan Stanley woes

Or take Amazon (AMZN), whose 1997 IPO was considered expensive after the company raised its offering price at the last-minute. Amazon’s shares languished for months after the IPO. But in retrospect, Bezos and Co. put to good use the additional cash they raised. With a market value of $97 billion, Amazon is now a giant worth more than 200 times more than it was when it debuted.

“It’s way too early to judge,” says Lise Buyer, about the Facebook IPO. Buyer is an IPO consultant in Silicon Valley who played a central role in Google’s (GOOG) IPO, while she worked for the search company in 2004. “Ultimately, what matters is how effectively the company deploys the cash that it raised. If it uses the extra dollars to build a stronger business, Ebersman will have done right by both the company and its shareholders.”

Regardless, Ebersman and Co. are likely to find themselves answering questions from plaintiffs’ layers, regulators and lawmakers for months to come. And in the meantime, the Facebook IPO debacle may serve a useful purpose: to remind investors big and small that IPOs don’t always go up, no matter how much hype precedes them.