UnitedHealth (NYSE:UNH) is the largest insurer, a blue-chip stock, and a Dow component, but does that make it one of the health-care sector's top dividend stocks? 

In this video, Motley Fool health-care analyst David Williamson will be grading well-known dividend stocks using a World Cup-inspired grading system: A yellow card is a warning for investors, a red card is an ejection, and a "goal" happens if the stock looks like a winner. 

Watch and find out the current strengths and weaknesses of UnitedHealth and whether investors should eject it.