This is the Emmit vs Barry Sanders debate all over again.
Back in the day, everyone knew that Smith was getting 3-4 yards before he was even touched. While Barry would lose yards all the time, but somehow break free to take over games repeatedly.
Of course, Barry had no FB and his QB was the biggest loser. (literally)
E. Smith was still a fantastic if not transcendent runner but there is no way that Barry Sanders would not have broken every record in the book behind that line.
Same thing with Lynch. Alexander was a great RB at getting behind his blockers and just bursting free. But you could knock the guy over with a can of compressed air. And he had one of the best OT to EVER play blocking for him, as well as one of the best guards in the league (Who was so good he made half of the Seahawk fans hate the Vikings for half a decade or more. The Vikings, a team that has done nothing since the 1960s.).
Lynch behind that line would be ridiculous.
It shouldn't even be a debate, Lynch is tiers better of a runningback than Alexander. Alexander is nowhere near an HOF type back. Lynch at his prime is arguably the match for many RBs in the HOF. There is only a longevity issue and I think even that will be offset by the sheer visibility of his successes on the field. He is the engine that powers the success of the Seahawks team, along with that defense.
Given how strong some of the teams in the SB chase were, including one of the best offenses ever, I don't think we would have even made it to the SB with Shaun instead of Lynch. But Lynch on that old Seahawk team with that line would have PWNED what turned out to be one of the weakest SB winners ever, that Steeler team. They would have lost by 14+ minimum, even with our safety getting beaten up by a street sign.
Lynch by miles and miles.(not even close)