Bringing in a 73 year old DC to run a brand new scheme was flawed. The scheme is okay, if you have the players to run it, and also the flexibility to switch out of it at times. But going into the season, pinning your success on the backs of a group of 30-something (or close) was flawed. I don't have a problem with what we did with LB's, because I thought they would fit just fine, but Carter couldn't cover anyone, and couldn't get off blocks. Installing a zone defensive scheme when you had three good man CB's was flawed. Even if Monte wanted to put in a Seattle-type single high safety scheme, that was flawed because we had no Earl Thomas type safety in center field.
We over evaluated what we had, which is something we tend to do regularly. Look at what Seattle did. They were a play away from the NFC championship game last year, with a very strong defense, and still went out and signed Avril and Bennett. And just drafting and signing more DL in the offseason wouldn't have necessarily been a better solution, but it would've been hard not be.