With their company's future at stake, Caremark ( CMX) shareholders face a fundamental question: Should they trust their CEO? Edwin "Mac" Crawford is urging investors to support an unpopular merger of equals with drugstore chain CVS ( CVS). Crawford insists that the combined company will emerge as a unique powerhouse that can drive valuable changes in the drug delivery business. He portrays a seemingly superior offer from Express Scripts ( ESRX), which would create the nation's largest pharmacy benefit manager, as unattractive in comparison. To his credit, Crawford has so far steered Caremark through a period of strong growth that has delivered solid shareholder returns. Less than a decade ago, Crawford rescued a company that was on the brink of bankruptcy by shedding its core physician management business and focusing on its small pharmacy benefit management division instead. Caremark was a modest player in a PBM world dominated by giant drug makers at the time. It grew with help from acquisitions and now ranks alongside Medco ( MHS) and Express Scripts as one of the nation's Big Three independent PBMs. These days, however, Crawford seems to be shunning the straightforward formula that has brought his company so much success. Moreover, he plans to step aside -- enriched by lucrative stock sales -- and leave CVS CEO Thomas Ryan in charge.