It's not that the MVC is wrong, it is that the model is not being built right. Moving to the BorrowABook feature is making a model class.
All too often in my experience I see code that has the model rolled into the controller. Controllers and UI are structurally supported better in frameworks. We get lazy and put model code into controllers. It is the way we make spaghetti code today.
The WWDC vids are in an app this year, not on iTunesU. Te an phones home to validate that you are a developer. It too is inaccessible now since dev center is down is down.
All too often in my experience I see code that has the model rolled into the controller. Controllers and UI are structurally supported better in frameworks. We get lazy and put model code into controllers. It is the way we make spaghetti code today.