Starboard Value Fund’s Jeff Smith pulled the trigger yesterday on his threatened attempt to wage a proxy fight at Yahoo, and he’s firing a large-caliber weapon – attempting to replace the entire board of directors. It’s the latest action in what is widely regarded as a war between Smith and Yahoo CEO Marissa Mayer. It is that for sure, but the proxy fight also highlights another important leadership story in this situation and many others, a story that’s often overlooked. It’s the leadership of the board.

Yahoo is one of two examples that are in the news, the other being the bidding war over Starwood Hotels and Resorts. In both cases the behavior of the board and the board chairman is centrally important because both boards made similar momentous announcements in the past 12 months. Last April Starwood’s board said it would “explore a full range of strategic and financial alternatives to increase shareholder value.” Last month Yahoo’s board said that “exploring additional strategic alternatives, in parallel to the execution of the management plan, is in the best interest of our shareholders.” Translation in both cases: We’re for sale.

When that happens, the board’s job is to represent the interests of the shareholders, and only those interests, with ferocious tenacity. Fortunately, both these companies have non-executive chairmen, which reduces the potential conflicts inherent in the old model of the CEO-chairman. But I’ll bet you can’t name the chairman of either company. At Starwood it’s Bruce W. Duncan, a longtime real estate executive and investor; at Yahoo it’s Maynard Webb, a veteran tech entrepreneur and executive who’s also on the boards of salesforce.com, Visa, and other companies. As both boards consider potential sales, breakups, or spinoffs, their job is to get the best possible deal for shareholders.

Duncan and the Starwood board have seemingly done a good job. After their announcement they negotiated with many suitors and reportedly scuttled a near-final deal after Marriott’s Arne Sorenson called at the last minute with a better offer. Then Wu Xiaohui of China’s Anbang Insurance lobbed in an even better deal — which Starwood’s board quickly accepted. And when Sorenson responded last week with a still higher bid, Starwood’s board accepted it. The board isn’t fighting with any potential acquirer; it’s doing its job of fighting for its owners.

At Yahoo we know only that no bids have been made public, but Smith’s letter to shareholders yesterday raises questions about the process. “Despite what appears to be strong interest from large strategic and financial buyers, as referenced in the media,” Smith writes, “nearly two months have gone by since Yahoo officially publicly announced its intention to pursue strategic alternatives for the Core Business, and it seems little progress has been made.” Smith suggests that Yahoo’s board is dragging its feet and says the issues “cast doubts…as to whether the process is genuine.”

Yahoo has not responded, and for now we cannot assume Smith is right. But we may eventually find out. In the meantime, these stories remind us that while CEOs get all the attention, boards are sometimes where the most important leadership is or isn’t happening.

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