Possibly by the middle of the bear they mean from top to bottom not from front to back. Shot placement is really important on bears for several reasons, first of all, in Sept. they have a lot of fat, up to four inches thick on a big one. Also their fur is really thick and because of these two reasons, blood trails can be an issue. You definitely need to get a pass-through if at all possible. You need to have an exit wound, and a low one is better. That is why I do not like mechanicals on bears, their ribs are wider and thicker than a deer's too. I have been using the G5 broadheads with terrific results.
I always try for a heart shot, and then you have some room for error--if you are a little off you will still get both lungs. Many people only will take shots at bears that are quartering away with their leg forward. In my experience that is a little too much to ask for. But shot selection is more important on a bear than a deer. Once you have to trail a wounded bear through super thick brush in the dark, you will know what I mean.
Good luck, hope you get one.