Rank and position are separate concepts.
As Data was second officer, he was higher in the chain of command than either Crusher or Troi. Besides, placing both of them higher is silly, given neither had much engineering/tactical experience. In a crunch situation, such qualities are needed. If I were an E-D/E-E bridge officer, I'd feel more comfortable heading off Romulans with Picard at the helm (or Riker or Data, even Worf) than Troi or Crusher.