Gruesome Ashmead's Kernel

Have the fruits grown too quickly with the deluges of rainfall this year, but the skin has been unable to expand at the same rate?

Well, it looks like that to me, but it happens every year and sometimes it doesn't rain all summer in Somerset!

I wouldn't be surprised if it's too much rain.

Other thoughts were the fruits being mildly attacked by scab (wet weather), which weakened the skin, which split and then healed again.

Possibly some manifestation of apple sawfly damage, but where the larva never managed to complete its task of getting to the core and eating the pips?
I do wonder whether AK has some kind of anti-maggot chemical in the fruit, as I rarely, if ever, find a maggot in an AK. Not that there are many pips in an AK for the maggot to feast on anyway; triploids don't produce many good pips - one per apple if you're lucky, with most "pips" in triploids just being a small, shrivelled, flattened, twisted brown-black speck caused by deformities due to abnormal chromosome numbers.

Also I wonder whether the pips (or at least any decent-sized pips) are all on one side of the apple, which encouraged lopsided growth and splitting as a result.
Try carefully dissecting one to see whether uneven pip distribution is causing the fruit to develop unevenly. The fact that AK is triploid is always going to make the seeds of por quality, and many triploids end up with unusual or lopsided shaped fruit.
Even Conference pears will grow one-sided or bent if pollination/seed-set is poor.

I've seen other people complain of the same problem in areas with plentiful rainfall. I've never had a problem like that on my Ashmead's Kernel/MM106, growing in a light soil in a low-rainfall area.
Even in this wet summer, I didn't get anything like that.
I get plenty of bitter pit on my AK's, though, but some of my bitter pit problem may be the MM106 rootstock not coping with my soil.

Incidentally, my AK's don't have more than one-quarter russet, and usually have plenty of orange stripes as they approach ripeness.
Here's a pic of a bunch of AK's ripening earlier this year, several weeks before they were ripe, so not showing the orange stripes.
Below it is a pic from a previous year showing a bad case of bitter pit (the apples were several weeks from ripening and the bitter pit got much worse).

While on the subject of gruesome......here's a pic of just how bad the bitter pit can get on quite a lot of my MM106-rooted bushes - almost any variety I grow on MM106 (and, oddly, sometimes M9 too) produces far too many really gruesome fruits like this.
Pears do the same when on Quince rootstock (but not on pyrus/pyrodwarf):

The tree is at the top of a bank which slopes gently down through a hedge to a roadside ditch about 12ft away, so it's well drained. I think my tree produces exceptionally thick-skinned, crusty russetty apples - is anyone else growing it, and how's theirs? As FB and I have the Yin and Yang of growing conditions . .