See Tszyu-Hatton. Similar result. I tend to see Arguello as far, far less capable at 140 than he ever was. He just didn't have it, and Hatton at his best was a pretty good tank. Alexis is several notches greater, but I don't think he beats a legitimate champion past his best and above his best weight.
The Arguello that fought Pryor would horribly obliterate Hatton(and the tszyu that Hatton beat too), even if he has looked stiff and uninspired in the 2 to 4 maulfest rounds it would take to detonate a right hand on the far too hittable and unimaginative hatton. hatton reports that the canvas feels bizarrely comforting on the side of his face after coming out of a 10 minute blackout.