The Sedins took the role of primary scorer after being secondary scorers. Edler was on the top pairing, but he was the defensive focus of that pairing. Now, Edler is the offensive focus.. if you had not noticed, Edler is better offensively than he was back then, but he's also much worse defensively now than back then.
Edler replaces Ehrhoff's role as the offensive side of the top pairing. Garrison replaces Edler's role as the defensive side of the top pairing. Does this not make sense?
How exactly is it a fallacious argument? If I have an answer for every replacement, then there is no fallacy.
Ehrhoff, Edler, Hamhuis, Bieksa, Salo, Ballard.
Edler, Garrison, Hamhuis, Bieksa, Tanev, Ballard.
Edler replaces Ehrhoff, Garrison replaces Edler, Tanev replaces Salo. Here, we have our replacements. It'd be stupid to say that Garrison replaces Ehrhoff because they do not play the same role. Garrison replaces Ehrhoff's roster spot, but not his role. Edler keeps his roster spot, but not his role.
I do not know if Green would make the team better, but if you asked me today, I would never do that trade. Having two goaltenders played a huge part in the Canucks winning two president's trophies in a row. Having the ability to stay at a competitive level if the #1 goaltender goes down is not a luxury but a necessity.