past unreal condition

[constantinusphilo]

If he was the only one they'd had to deal with he would have landed us all in the
gas chamber.
The Secret History, Donna Tartt

I think 'was' here is due to the colloquial style, otherwise, 'had been' is grammatically correct. So the correct version would be: If he had been the only one they had to deal with...
Somehow, she has messed it up, I think.

 

[jutfrank]

Why did you correct they'd had to they had? Was that intentional?

 

[constantinusphilo]

Why did you correct they'd had to they had? Was that intentional?

Yes.