I do think Elway thought Defence after he built a juggernaut Offence and that is the achilles heel of an offensive minded QB/GM.
Sherman is also correct about Manning, he throws ducks. Short crossing patterns was Seattle`s Defence wheelhouse with shut down corners.
Denver was tailor made for Seattle. Tough defensive teams like San Francisco, Carolina or a big arm QB that can threaten their corners like Luck of the Colts give the Seahawks more problems than Denver ever could.