Edman hasn't been overrated as much as he has been overused. For a long time he was leading the majors in at-bats and leading the Cards in innings played at two positions. It's just too much.
There's a familiarity there, and Colorado has a habit of developing hitters the Cardinals can't and have not and not locking them up long-term.
Votto's been able to adjust his swing more often and later in his career, as Carpenter seemed to adjust his swing and never be able to adjust it again. He made the changes for big power but has never found a pull-back to beat the shift as that power faded. Votto's also a better player, and I don't mean that as a knock on Carpenter. Votto's a potential Hall of Famer. His downs were not as severe, and have not lasted nearly as long. Also his home ballpark helps.
Any team in baseball would be wise to see if they can poach some of the Brewres front office. They're the most impressive group going right now.
Injuries were a big factor in 2011 too. Pujols was out for a bit as things got really bad. The Cards have been injured this season but not drastically compared to what other teams have overcome. The 2011 team was wild talented but had not clicked and had not been healthy. I think they're pretty different, as you suggested.