I'd suggest the Deans sides were under-coached, which isn't something I'd say about the Rennie Wallabies so far. We seem very tactical, very planned, very coached.
I'd suggest Wisemantel is behind the tactical side of things. I can see Scott Wisemantel's fingerprints all over these Wallabies. Very organized, pre-ordinated, step-by-step actions. Identical to England under Wisemantel. Like a game of chess, very pre-planned, calculated movements.
By the looks of things Rennie is filling a more inclusive, coaching co-ordinator role (much like Graham Henry did), as he has 4 assistant coaches, Du Plessis, Wisemantel, Parling, Taylor, that are all heavily involved in strategy. Rennie has admitted this in interviews, it's why he made it imperative to surround himself with highly qualified & experienced technical coaches.
Deans didn't have this option. Deans had a bunch of in-experienced duds foisted upon him, and he didn't have say in the matter. He didn't get to hand-pick his assistants, unlike Rennie. The role of the head coach these days is more of a directorial/manager type role, where you helicopter over the group, instead of actually being heavily involved in the technical/tactical side of things.
It's all very dependent on who your assistant/technical coaches are. Case in point - In 6 seasons with the Chiefs, Rennie only won the Super Rugby title in the 2 seasons in which the great Wayne Smith was his technical advisor.