Tomato blossom end rot

I inspected one of my largest beefsteak legend tomatoes today and got the shock of it being rotten underneath 



I don't understand how it got blossom end rot, there are plenty of nutrients in the potting mix (compost, worm castings, rock dust, blood fish bone) and I water pretty much every day unless it's been pouring. I've never left the soil to dry out.

But then I inspected the others and now I'm worried.





Either this rough looking bottom is characteristic of the 'legend' variety, or pretty much my entire beefsteak crop is developing BER...

Any advice would be appreciated. I of course would prefer to hear it's characteristic of the type and not rot, but best get the truth on this one. I'll be very annoyed if it is rot because as far as I'm aware I've done nothing wrong.

A lot of beefsteaks has ugly bottoms, "Brandywine" for instance has them more often than not.

I think this is what it is, rather than blossom end rot.

It's my first time growing beefsteaks so if it's normal for them to have a bad looking bit at the bottom, I'm still learning about that. But I'm fairly sure the top image is BER as it is a large dark rotten looking blot on the bottom of it.

My yellow brandywines had the ugliest bottoms I've ever seen! 

Still tasted good though!

Oh deary me, just wait for someone to take this topic " off topic" my bottom isnt pretty either