I agree, Calzaghe would be a nightmare for Froch. Eubank I'm not so sure, although he could be evasive at times which Froch hates, so I'd possibly give him the edge.
I think Eubank, Benn, Calzaghe, and Watson would decision Froch. The fights with Benn and Eubank against Carl would be epic.
He'd get outclassed by Calzaghe, probably wins a couple of rounds but never in the fight, bad style for Froch and also better fighter. As said Eubank's movement and reflexes would see him beat Carl, although Froch's output and Eubank's tendency to not throw enough see it being competative. Favour Froch over Benn, at 168 Benn doesn't have to power to stop Froch early and see Froch increasingly taking over down the stretch. Haven't seen enough of Watson or Collins to say.
Like others, I reckon he could stop Benn. I don't know enough about Watson to speculate about that figt. Collins woul have been too smart. Calzaghe would have been too...everything. I think he would ultimately lose to Eubank, but that would have been fun to watch. Froch had better stamina and I figure he would have used his stamina and awkwardness to make long stretches uncomfortable for Chris, who would slide around, landing evil shots at every opening.
Froch's lack of speed doesn't bode well for the match-ups with the speedsters and the skillful movers. Benn, however, would stand right there, and Froch is INCREDIBLY tough and very strong and powerful. I give him the edge in that match up, styles, Benn not being at his best, etc.
Eubank: Eubank UD Benn: Froch UD/Late TKO Watson: Watson UD/SD Collins: Froch SD Calzaghe: Calzaghe UD
Fighter's who trouble Froch the most are well schooled and technical. Dirrell gave Carl problems , not with handseed but by fighting on the backfoot. Calzaghe would not be fighting off the backfoot looking for countering opportunities , he would be coming at Carl with voloume punching. This tactic would play right into Carls hands. The speed wont bother Carl and he will eat a few to land his jab and overhand right. He might be getting outboxed but Joe is slowly getting chopped down and taking the worst out of the exchanges. Carls patience and timing couldl result in a late KO victory.
Calzaghe and Frank also wanted no part of Carl and dropped the WBC belt when Froch became his mandatory.
Calzaghe - wide Calzaghe decision, far too much speed and movement for Froch Watson - Watson UD, 1 of the best technical boxers Britain has ever produced, a shame his career got cut short before it got going Benn - 50-50 Froch isn't the best inside and his low hands give Benn , still Froch is bigger and maybe has the jab and strength to push Benn around Eubank - close fight, Eubank is more skilled and quicker, Froch has a good jab and workrate to bother Chris though Collins - Froch UD - better basics win out
Eubank - quite a comfortable schooling really, the difference in foot speed and flexibility being immense. Eubank PTS. Benn - Benn only needs one chance to step in and lay a right hand on. Benn KO in less than six. Watson - Mike would struggle with Froch's long jab and long uppercuts because he was a bit static and ear-muffy. Froch UD. Collins - Collins would've outfoxed him, probably coming at him from awkward angles to neutralize the Froch jabs and uppercuts. Calzaghe - Calzaghe is very hittable and Froch can hit, especially with the right uppercut, which would be perfect against a square-on, rushing southpaw. Froch KO, in the middle rounds.