Unfortunately this is the case. Rocky was a tank of a man. Tua is a bigger tank with thicker armour, albeit with a smaller fuel tank. Tank battles are not won on fuel capacity though.
This is why matching up fighters from vastly different eras is so fruitless. The idea of a footnote like Tua beating a great like Rocky is sickening.
Tua is 1-0-1 against Raahman. Raahman fought twice with former middleweight Toney and couldn't beat him either time.
Stylistically they are very different though. Byrd is a mover, Toney is a stationary counter-puncher who'd be in Tua's range much more often.
Tua Versus Rocky? I'd give it to Tua. Rocky had a tendency to cut really easily. A Left Hook from Tua may have Rocky bleeding beyond repair. Plus, Rocky never fought a 200 pounder with power like David Tua. And if Walcott and Moore could drop Rocky, I'm convinced that the powerful left hook of David Tua would drop Rocky and keep him there.....