you cannot go against Foster. I will be honest though, one style which would be hard for Calzaghe at light heavyweight is Virgil Hill. I am not sure Calzaghe would have an easy time with the Virgil Hill of 1992 or 1993.
It's the old technique of embellishing someone's legend by saying he would make the modern day fighters **** blood. It's all hypothetical nonsense.
Foster wasn't exactly a speed demon and his footwork while solid he certainly wasn't what you'd call a speed demon. If Calzaghe stayed out of Foster's wheelhouse I could see him slipping and slapping to a close decision. But I wouldn't place a wager on it.
Foster had very quick hands actually. And its not like Calzaghe has great footwork, and defense. This is a mismatch... anybody giving Joe a chance are either EXTREMELY overrating Calzaghe, or have never seen Foster fight.