I mainly work with big rolls of batting...but every once in a while I will get to work with packaged batting. Usually it's fine. But sometimes it's not!
..oh yes! That is one big bubble! So I have come across this a few times and I found the best way to fix this is to cut off the extra batting...or you could say stretched batting..
I cut a slit..then lay the batting flat..and then cut off that extra batting you see in the picture above.
This is bad picture but if you look close, I then stitch the slit together with a fairly large stitch and it works great!
One more thing. Packaged wool batting is one of the worst as far as wrinkles...bad wrinkles! I found the best way to handle that is to open and spread out the batting the night before you are to use it and the next day all the wrinkles have disappeared!
Hope this helped for anyone that has come across these situations before.
Your welcome to add any tid-bits on this matter.