They may have been overripe. When pears are past their peak they start turning brown and soften from the core outward. Such pears aren't actually spoiled, the flesh is just breaking down as a normal process in the late stage of ripening. In that condition you can still make sauce or pear butter, or cook them. They won't look as pretty cooked, but they taste fine.

Some related pome fruits that are usually hard and astringent don't become edible until they get to such a state. The main example of this is the medlar, and there are others such as Sorbus domestica.