Could be over watering for the splitting an maybe grubs for the wholes what I do to Prevent this is I pick my tomatoes an soon I spot The smallest shade of orange or red an place the tomato in my window to finish ripening without fear of bugs :)

Looks to me like vertebrate pests; my money is on birds. They tend to be attracted to visible ripening fruit, and stab it with their beaks. I get very similar marks on my nectarines.

Rats will sometimes get to ripening fruit which is more buried in the plant, but they leave distinct small tooth marks and ragged edges, not these neat slashes.

You can protect the fruit by putting a cover over the fruit so the birds don't see it; paper cones or baseball caps (fix the back strap around the stem) seem to work well. More concealed fruit should be safer.

--Alison