That explains the difference in what we were seeing in different worlds, but it doesn't answer your complaint, if it actually happens. You seem to insinuate that players drop their demands during FA period (i.e. they will sign a 1 year deal). But after FA period, the demands raise again (i.e. they won't sign 1 year deal). Then, during spring training, the demands lower again. I can't say that I've ever seen this, but can't say that I've paid close enough attention either.
Did you ask CS about this? If this is how it actually works, then I agree that it's not very logical. It seems the logical solution would be a gradual drop of demands from the start of free agency to the end of spring training.