Was Shelley Hack too unconvincing as an ex-cop?

In other words, you could within reason, believe that Kate, Jaclyn, Farrah, and Cheryl could get through the police academy. But in Shelley's case, didn't she look awfully geeky and uncoordinated? Plus, she came off as sort of an airhead instead of a rough and tumble cop. Her whispery voice didn't help either. It didn't help that Shelley was brought replacing Kate Jackson, who was seen as the smart one.