Mainly off the back of looking good for a few rounds against a plodding Louis, his LHW resume isn't particularly strong compared to the greats and he doesn't have a win on his record on par with Hopkins. If we compared Calzaghe's SMW and LHW, which would encompase the LHW division of Conn's day Calzaghe probably has the better resume. He fought journeymen at HW Louis aside, Calzaghe would sweep them aside pretty easily. I'm honest with how I call them
He stopped Bob Pastor. The only other man to stop Bob Pastor...Joe Louis. Pastor was an absolutely excellent heavy. I would pick him to beat Joe Calzaghe.
The only two fighters Calzaghe fought above 168 both dropped him on his ass in the first round and both were over 40 years old. Louis would destroy him.