I defy anyone to name a big fight the past 20 years where one of the following has not been brought up:

He was past his prime
He hadn't yet reached his prime
He moved up too far in weight
He had to cut too much weight and was drained
The ref stopped it too soon
His trainer gave him a massage the night before and his legs got tired
He hurt his hand
He was fighting with the flu
9-11 had a bad effect on him
His sister was going to jail and he was distracted
He didn't train
The headbutts affected him
The hometown ref let him get away with too much rough housing
He really won, it was a bullsh!t decision
Even though it was stopped on cuts, he was on his way to knocking him out
He was inactive for too long and lost because he was rusty
The guy he beat was overrated to begin with
His corner gave him bad advice