Aside from the fact it is wrong to both weigh in at below weight to fight on the night on or over the weight for a belt at a higher weight than weigh in.
I still recon the 155 weigh in suited Kahns fight better than it could of Canelos as I think Canelos style can hold weight.
Im thinking If Kahn weighed more on the night he would of been slower and only lasted a round or two until being caught even harder than he did.