Yes , once they get soft they usually are rotten. They do this from the inside out. The soil that they are in does not look like potting soil,which is what they should be planted in. Also looks like you have peeled off some of the outer layers , also something that could cause problems. Hope this helps.

I can't quite tell from the photo... it almost looks like a flower scape died and is rotting under the first layer of live tissue. Is there only that one visible spot that is dark? I have had some bulbs that developed rot from the inside. I assume it's from water getting in between the bulb layers from rain/water getting into the neck of the bulb.