It is "rain cracks". They take on excess water and swell soo fast they will crack. It is not a big deal if you are canning them but for years we were the exclusive suppliers of tomatoes and green bell peppers to four supermarkets across the river in Iowa. There was no way you could take them any cracked fruit. We did not irrigate so we could not control the rain but it did require good sorting. We had to clean, polish, and box them into 20 and 30 lb lugs. Then deliver them to the store. They paid us $0.30 per pound. They then took them out of the lug (box) and put them in the produce counter on "sale" at $0.99 per pound. It got to the point they claimed they were not making enough money and started buying through Nash-Finch and had them trucked from California.