For an outside the box take, I'd propose that Lanning himself may be the best OC the Ducks have had.
Early in his coaching carrier at UO, Lanning said that the offense would be a blend of his, Dilly's and the position coaches concepts. He also said that for years, he and Dilly would bounce ideas off each other to get a better understanding of how an offense or defense would respond to a certain type of play or formation. Lanning said that a better understanding of offensive scheming made him a better defensive coordinator. When Stein took over for Dilly, Lanning said that the offensive scheme already in place would remain in place and Stein would be adding his takes to the mix.
Bottom line, this offensive game plan is baked into Lanning's offensive philosophy and will remain regardless of who the offensive coordinator is.