It might be time to change I.B.M.'s nickname from Big Blue to Black and Blue, given the beating the computer giant has taken lately. Deep cuts in the work force, multibillion-dollar charges against earnings, a plummeting stock price, the loss of its blue-chip AAA bond rating -- a humbling litany indeed for the International Business Machines Corporation, the company once revered worldwide as the epitome of management excellence and technological prowess. Still, the bad news has been good news for a pair of I.B.M. watchers whose timely critiques of the company's plight are making them the talk of the high-tech community: Mark Stahlman, a New York-based financial adviser, and Charles Ferguson, a consultant from Cambridge, Mass. The two men are, in essence, vying for the distinction of being America's leading I.B.M. basher. The rewards, of course, are a public following for themselves, the books they are writing and their advice-selling firms. How times have changed.