I assume the anchor text is just big blue widgets.com and then descriptive text.
In your example (with spaces), Google will index you for "big", "blue" and "widgets.com".
If the link is "big-blue-widgets.com" it will be the same as above. Hence keyword domain advantage.
If the link is "bigbluewidget.com" then you get no keyword anchortext.
It makes sense to ignore the domain if google wants to tackle keyword domain advantage, but at present I don't think they do.
The words surrounding anchor text, perhaps up to five, are related to the link, so "custom" will be associated with the link text. In this respect a better link would be "Big(space)blue(space)widgets(space).com - Custom made widgets.