Carly Fiorina has taken a lot of heat over her business record. But evaluating her performance is more complicated than it seems.

Shares of Hewlett-Packard, the tech giant she ran from 1999 to 2005, fell 45% during her tenure, and she was thrown out as CEO. That doesn’t sound great.

During Wednesday evening’s Republican debate, she tried to blunt some of that criticism with context. Basically, Fiorina said you have to look at what was going on at the time, and that’s a good point. Fiorina took over HP HPQ toward the end of the tech bubble, and she only held onto that job for the first few years of the economic downturn. It was a particularly tough time for large computer manufacturers, of which HP was one of the biggest. “I led Hewlett-Packard through a very tough time, the worst technology recession in 25 years,” says Fiorina.

But even when you compare Fiorina’s performance to CEOs who had to navigate the same waters, it’s hard to defend her track record. At the debate, Fiorina noted that the NASDAQ stock market index, which contains a lot of tech stocks, fell 80% while she was CEO. She said HP had a lot of strong competitors and that some of those went out of business, eliminating all of the jobs at those companies.

The NASDAQ figure she cited reflects the index’s fall from its peak in early 2000 to its bottom in early 2003. During Fiorina’s full tenure at HP, the NASDAQ fell just 23%, or half as much as HP’s stock. IBM, which Fiorina viewed as a model, struggled during the period that Fiorina was CEO of HP. But its shares did better than HP’s during the time, falling 29%. Other computer companies did go out of business, but few did during the time period Fiorina was running HP. A major competitor, Digital Equipement Corp., or DEC, was acquired by Compaq, which was later bought by HP. Gateway is no longer in business either, but it was acquired by another computer maker, Acer. Xerox stopped selling personal computers, but it is still in business.

Shares of Dell, on the other hand, were up 11% during Fiorina’s reign at Hewlett-Packard. What’s more, HP’s crown jewel was not its computer business, it was the printer business. Shares of Lexmark, a competitor in that business, rose 29% during Fiorina’s tenure.

Fiorina also said on Wednesday evening that while she was CEO of HP, she “doubled the size of the company, we quadrupled its topline growth rate, we quadrupled its cash flow, we tripled its rate of innovation.”

When it comes to size, it’s not clear what she is talking about. Typically, Wall Street thinks of the size of the company as its market capitalization, which is the total net worth of a company. But like HP’s stock, that dropped during Fiorina’s stint as CEO, from $106 billion to $56 billion. Fiorina could have been talking about sales, which did double during her tenure. But, as others have pointed out, that was largely because of HP’s acquisition of Compaq. Before that deal in 2001, HP had $45 billion in sales and Compaq had $33 billion. When Fiorina left in 2005, HP’s sales had grown to $87 billion. So, even factoring in the acquisition, HP’s sales rose by $9 billion over three years.

That’s only a growth rate of around 3.5%. In the three years before the Compaq deal, HP’s revenue growth averaged just under 5%, and Compaq’s had been 20%. Again, IBM struggled during the same period, but its sales rose an average of 5%.

HP’s cash flow did grow under Fiorina, but not by as much as she claims. HP’s earnings before interest, taxes, depreciation, and amoritization, or EBITDA, which is the way Wall Street usually measures cash flow (its earnings before non-operating expenses) was $4.8 billion in HP’s fiscal 1998, which ends in October. By October 2004, Fiorina’s last full year as CEO, it had reached $6.8 billion. That’s an increase of 40%; not bad, but far from quadrupling, as Fiorina claimed.

It would be very hard to measure HP’s “rate of innovation,” but the defining move of Fiorina’s tenure at HP was the acquisition of Compaq. Fortune published the definitive take on that merger. It didn’t go well. That being said, HP is still around, unlike some of its competitors, as Fiorina points out.

Doing some kind of transformative deal was probably the right call for the company, even if Compaq didn’t work out immediately. Eventually, it led to big changes at HP that were for the best. HP has had some good years since Fiorina left the company. Earnings nearly doubled the year after she left, which Fiorina gets no credit for but probably deserves some.

HP is struggling again. It is breaking itself up, and recently announced layoffs. How much blame or credit Fiorina deserves for that is hard to determine. At this point, she left the company more than a decade ago.

Fiorina may turn out to be a good candidate, and perhaps a good president. But her run as CEO, well, it just wasn’t all that great.