Still a nice tomato!
Looking forward to what your bigguns will weigh in at!
I can't tell clearly from the picture but the smaller side of the tomato looks like it is a fair distance away from the stem. If this is the case, the tomato 'pulled' away from the stem from its weight. It causes the bit that the stem separated from to grow at a slower pace and ripen prematurely.
Below is an example:
image.jpg
Supporting the tomato at a small size will most likely prevent this.
Also, cover the fruit with white cloth to reflect the light/heat to slow down ripening if you already aren't doing so. It works a lot better than covering with the tomato plants leaves.
Hope this helps
