[Grammar] "had left" or "left"?

[simile]

Hi, I wonder which one makes sense in this context:
If they left home ten minutes earlier, they might have caught the airplane.
If they had left home ten minutes earlier, they might have caught the airplane.
"left" or "had left" makes more sense? Which one is the better writing style?
Thank you for your reply!

 

[abaka]

In a hypothetical phrase, say "if they had left". Observe the sequence of tenses: had left, might have caught.

The first sentence means something else: Since they left ten minutes earlier, it is possible that they caught the airplane. But it needs context to work well, and even in context the substitution of "if" for "since" is very casual.