Hmm. I haven't heard of that one, but meat does age even after it's been frozen, if we leave it in the refrigerator for a few days. There's no reason it shouldn't, because the same enzymes are present.
We do tend to drain meat of the extra blood if we do that, and then dry it further before cooking, which results in a better browning on the outside. But I have no idea if leaving it in the blood has any effect on tenderness. I'll have to ask mizwhitetail: She has all the latest meat research in her files, and might have seen something on that.
