Excuse the bodybuilding example here, but this thread heads in that direction.
But if you do a late flare, you will notice your pecs are tensed somewhat, I think. Maybe stretched, or both at the same time.
I'm not sure of the research location, maybe
@Kenny Croxdale can chime in.
But I remember reading somewhere that stretched under load can cause the muscle to grow.
Probably not as much as exercises targeting the chest directly, but a program like ROP has definitely firmed up my chest considerably, and I'm not even doing pullups, just hangs.
For example, consider the dumbell pull over. Is a snatch and a pullup not basically the same movement?
Catching the clean forces you to naturally tense your chest, and support required, the "shelf" is not only the lats but also the chest.
Just my thoughts.