The doctor was angry. Not long after Blue Cross Blue Shield of Massachusetts urged him and other health care providers to keep their costs down, the insurer this month disclosed it had agreed to an $11 million payout for its former chief executive. In a terse voicemail, the physician told Blue Cross: You have a credibility problem. It was the kind of call Andrew Dreyfus expected. Hired as CEO of Blue Cross last fall, Dreyfus has been championing affordability — prodding payers and providers to work together to rein in the price of medical care following years of double-digit insurance premium increases. Then came the uproar over millions of dollars collected by his predecessor, Cleve L. Killingsworth, and headlines about five-figure annual fees paid to board members. Suddenly, the talk about lowering healthcare costs rang hollow. To many, Killingsworth's pay package and the board's fees— which were suspended more than a week ago in an effort to diffuse the public outcry— undercut Dreyfus's call to control healthcare spending. "It's hard to reconcile those two messages,'' he admitted.