It is interesting in the era of nutrionists it happens so frequently. I think it's because some fighters know if they move a weight class up-it's their ass.

R.I.P Diego Corrales comes to mind; Pissed that Castillo failed to make weight- then his next fight it happened to him. To hungry & incapable to make weight, but got blitzed by Joshua Clottey when he did move up. Same happened with Nate Campbell- I think he tried to make weight (and failed) because he felt he wouldn't be able to deal with the next weight class.