Calzaghe certainly could outbox Benn, but I believe Benn could've KO'd Slappy with one punch if he caught him flush.
The dream about the one big punch landing never comes true. You want a KO, you have to outbox the other guy first. Benn would have been badly overslapped against Calzaghe.
I think Benn would hurt Calzaghe early before being outhustled and outworked in the middle rounds and getting stopped on his feet late.
I would have loved to have seen Calzaghe in the Benn / Eubank / Watson era. I am certainly no JC nuthugger but I do believe that he would have come out on top. Nigel Benn is one of my all-time favourite boxers but he lost to Eubank, Watson and Steve Collins (twice). It would have been damned entertaining (as with almost every Benn fight) but he would have lost to Calzaghe too if they'd met in each other's pomp... No disrespect to Nigel, he provided us with some fantastic nights of entertainment and was a true warrior but he definitely had his limitations.