We all know tomato fruit splits due to uneven soil moisture (i.e. wet and dry period) and/or the inability of the plant to take up enough moisture during fruit development.
When moisture uptake is limited, tomato fruit stops enlarging and the skin of the fruit goes from the consistency of flexible rubber to the consistency of a brittle plastic. When the plant again moves water to the fruit, the fruit begins to enlarge and the skin cracks.
The cracks on some varieties of tomatoes will form concentric circles around the stem while other varieties will crack from the stem end toward the blossom end. To prevent this from happening we need to keep the soil uniformly moist and improve conditions that will allow the roots to move water to the leaves and fruit.
When some tomatoes crack and again start to grow, they grow out of the crack producng strange looking fruit. Split fruit are also highly susceptible to various rots.