When he became chief, many people wondered whether Mr. Cook, a skilled manager of Apple's operations, could ever rival the visionary influence of Mr. Jobs on Apple products. Instead, it appears Mr. Cook could make his earliest and most significant mark by changing how Apple's products are made. ''I want to give credit to Tim Cook for this,'' said Dara O'Rourke, associate professor of environmental and labor policy at the University of California, Berkeley. ''He's admitting they've got problems.''
