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As a general rule, hedge funds are not shy about letting companies know what they can be doing better.

But Starboard Value took that outspokenness to a new level when it published a blistering 294-page critique of nearly every business practice at Darden Restaurants — down to how many breadsticks servers at its Olive Garden chain brought to customers’ tables. And then Starboard put on its chef’s toque and took aim at how Olive Garden prepared its pasta.

“Shockingly, Olive Garden no longer salts the water it uses to boil the pasta, merely to get a longer warranty on its pots,” the hedge fund declared, later citing the New York restaurant Frankies Spuntino in calling for “Atlantic Ocean” levels of saltiness.

In years past, that broadside might have turned off the staid mutual fund managers who dominate Darden’s shareholder base. Not this time, though. Starboard succeeded in ousting all 12 directors at the company’s annual meeting in October, a stunning repudiation of the existing board.

The victory reflected the continued power and prominence of activist investors like Starboard — hedge funds that call for shake-ups in the hopes of squeezing out higher returns for themselves and other shareholders. One of the common complaints of activists is that corporate boards are too complacent and do not push executives hard enough.

Leading the charge have been some of the most prominent hedge fund managers. Daniel S. Loeb of the hedge fund Third Point all but claimed victory over Sotheby’s this spring when he gained three seats on the auction house’s board in a settlement. Carl C. Icahn, whose experience as an activist stretches back three decades, has prodded for changes at companies including Apple and Hertz. And William A. Ackman of Pershing Square Capital Management successfully pushed the Botox maker Allergan into selling itself, reaping a multibillion-dollar trading profit even though the drug manufacturer did not merge with Valeant Pharmaceuticals, his partner in the takeover attempt.

In some ways, these corporate rabble-rousers reached new peaks in 2014. About 281 activist campaigns have been announced so far this year, according to FactSet, the highest level in at least five years. The activists have largely prevailed in these battles, enjoying a 72 percent success rate, or nearly double the rate in 2003.

Even companies once considered too big for activists to take on, like Apple and eBay, have been forced to hold discussions with them. These discussions have often yielded at least some change in corporate strategy: Apple has steadily increased the amount of money it returns to shareholders in the form of stock buybacks and dividends, and eBay plans to split itself in two.

Activism is expected to remain a strong force. Nearly every respondent to a recent survey by the law firm Schulte Roth & Zabel expected activism levels to rise next year.

The successes have not only swelled prominent activists’ war chests, giving them the ammunition to fight new battles, but have also won them support from other investors. A brand-name activist who acquires a significant stake in a company often has the silent backing of other shareholders, making the investor more formidable in negotiations over representation on the board or other concessions, according to Jesse Cohn, a portfolio manager and head of equity activism in the United States at the $25 billion hedge fund Elliott Management.

Perhaps the biggest recent change, say both those on offense and defense in the activism game, is the higher level of engagement between the two sides. Many potential battles are now resolved before the hedge funds publicly declare war through moves like proxy fights, usually with activists winning a board seat or two.

“There should be a much more constructive dialogue, and for the most part there is,” said Mr. Cohn, whose campaigns this year have included pressing the data storage giant EMC to break itself up.

Even mainstream investors — including mutual fund managers like Fidelity and BlackRock — have become more emboldened to talk to management about their concerns, at least in private. Before, representatives of these firms would have shied away from such discussions, fearing that they might lose access to senior executives. Now, though, they feel more confident about speaking their minds, said Jason Truman, a Morgan Stanley managing director who heads the firm’s activism defense practice in the Americas.

“Where I have seen a change is in private interactions with management, when shareholders have been much more upfront about what they want,” he said. “That’s been a big change, since that’s been a big river for shareholders to cross.”

Just the prospect of a fight with shareholders has prompted some company directors to begin preparing defenses. Corporate advisers say they have been increasingly hired to help companies survey their strategic options and coach boards on how to deal with potential activists.

And some boards have gone so far as to shift strategies before a campaign has even begun: The Madison Square Garden Company disclosed in October that it was exploring the idea of breaking itself in two and that it planned to add two new directors, including the veteran activist Nelson Peltz, to its board. (Mr. Peltz did not own shares in M.S.G. beforehand, though another hedge fund, JAT Capital Management, disclosed this summer that it owned a significant stake in the company.)

Of course, not everyone on Wall Street believes that the wave of activism is a good thing. The staunchest defender of corporate boards, the law firm Wachtell, Lipton, Rosen & Katz, argued in a recent memorandum that such activist campaigns proved harmful for companies in the long term. Among its concerns, the firm questioned whether hedge funds were better qualified than management teams to weigh in on basic operational matters.

And some activists have said privately that the success of their strategy has drawn many more competitors, potentially leading to overcrowding and lower returns. Firms that call themselves activists reported an average return of 4.5 percent for the first 10 months of this year, according to Hedge Fund Research. While higher than the average hedge fund return of 2.8 percent for the same period, that trails the 9 percent gain posted by the Standard & Poor’s 500-stock index.

Some advisers on the defense side have also questioned how the investment strategy will fare if the markets begin to slip. Such a decline may limit some of the moves that activists have been pushing for, from corporate breakups to acquisitions to borrowing more to pay out special dividends.

Still, Wachtell has been forced to concede that at least engaging with these investors is now all but inevitable. “Directors should develop an understanding of shareholder perspectives on the company and foster long-term relationships with shareholders, as well as deal with the requests of shareholders for meetings to discuss governance, the business portfolio and operating strategy,” the law firm wrote in a public note.

Activists say that they will continue to fight with companies so long as there is no other way to push for changes in strategy.

“The only way to get these executives off the golf course is to file a 13D,” said Thomas Sandell, chief executive of the hedge fund Sandell Asset Management, referring to a disclosure that activist investors usually file with the Securities and Exchange Commission.