I would say that these became mixed conditionals through the substitution of
were for
had been,
which is a common substitution, especially in everyday
conversation. I would say that the 'original' thoughts and
meanings were:
If you had been paying attention, it wouldn't have happened.
If she had been working for him, he would have protected her.
(The versions with
were-substitutions have the same meanings as the 'originals'.)
__________
As for the substitution of the simple past:
If you paid attention, it wouldn't have happened.
My personal feeling here is that to get the same meaning as the original, it should be
If you had paid attention, it wouldn't have happened.
This one usually refers to an individual act of paying attention,
whereas the one with the progressive usually refers to a period of time
filled by the activity of continuous attention-paying.
Compare:
The fire alarm went off, and believe me, when an excited voice came over the speaker system, everyone paid attention. (Everyone immediately became alert to the situation.)
There was a ladder against the wall, but I wasn't paying attention, so I ran right into it and banged my head. (I was not continuously alert to such dangers as I was walking.)
__________
If she worked for him, he would have protected her.
Again, my feeling is that this should be
If she had worked for him, he would have protected her. This example is a little different from the 'pay attention' example. I hear the difference like this:
Progressive:
If she had been working for him (at that time), he would have protected her (then) (at the same time).
Simple:
If she had (ever) worked for him (at any time before
that), he would have protected her (either while she had been working
for him or after she had finished working for him).
CJ