Does it matter that he is assigned to a station or not?

On my vice admiral engineer I removed my efficient BO from his station and replaced it with a normal BO and all ship power levels remained the same.On my lt commander sci(he is efficient captain) I get +1 engine/shield/aux if I use my efficient saurian in the science station instead of a normal BO.This is a bit confusing.

I ask this because it is not nevermind that I buy a few engineer saurians for 29 mill./1 or I buy tacticals for 49 mill.(the current price).