CIO — Bigtime CIOs have endured a volatile year, and their wallets have felt the impact. The sour economy and politics involved have led to a huge drop in performance bonuses and rejiggered our annual list of high-paid technology leaders.

But the decline in top pay may be temporary. In the past, public companies often used vague language in its annual proxy report to the Securities and Exchange Commission, saying things like "compensation is tied to profitability or revenue growth" without spelling out how. Now the SEC demands more detail about how companies pay their executives. Kevin Nussbaum, vice president of new client development at professional services firm CBIZ Inc., predicts the new transparency will ultimately result in even higher pay for superstars.

[For more detail on top CIO salaries, see our chart The Richest CIOs: Our Annual List of Top Earners. ]

Most striking this year is how discretionary pay has plummeted with 37 of the 52 on our list earning no bonuses. We compile our annual list by studying the SEC filings of the 1,000 biggest U.S. companies to see what compensation looks like—including salary, bonuses, perks and incentive pay such as stock and options awards—for CIOs ranked and rewarded highly enough at their companies to be included. Just three of this year's top 10 received bonuses.

There's also been a lot of turnover: Seventeen CIOs on last year's list didn't make it this year. Some have left their jobs, including Mark Boxer, former CIO of Wellpoint, who retired; and Linda Goodspeed, former CIO at Lennox International, who is now VP of Information Systems at Nissan North America. Last year's number-one, Barbara Desoer, who earned $10.5 million at Bank of America, was promoted to president of the bank's Mortgage, Home Equity and Insurance Services business. Others remained but dropped out of the circle of top five highest-paid officers at their companies, such as Robert Carter at FedEx, Dave Kepler at Dow Chemical and Thomas Kingsbury at Kohl's.

To explain why the SEC's changes could lead to big bumps in compensation for the top 25 percent of CIOs and other executives, Nussbaum compares them to compensation practices in professional baseball. The disclosure of contracts and the umpteen statistics tracked in the Major Leagues have helped superstar players get multimillion-dollar deals. Each home run, in essence, is worth so many dollars. CIOs who are negotiating pay packages may also use the numbers now available to them. "The data will be specific enough to compare across companies, like in baseball," he says. "They'll say, 'Look, company A had these targets. We performed above that. I should make more than that CIO.'"

For example, discount retailer Big Lots spelled out that CIO Lisa Bachmann earned a 6 percent raise, from a salary of $413,000 in 2007 to $436,000 in 2008, for helping improve inventory turns by 3 percent and launching both a new point-of-sale system and a multiyear migration to SAP. And 73 percent of her total compensation last year was "at risk," meaning subject to meeting performance goals. The company also lists 16 competitors against which it compares its compensation practices.

The key, of course, will be to rack up IT homeruns. So far, there are no performance-enhancing drugs for that. Just hard work.

Follow senior editor Kim S. Nash on Twitter@knash99. Follow everything from CIO.com on Twitter @CIOonline.