I'd rather have Eberflus if he's ready (or keep Marinelli). Eberflus knows the division, he knows the players and he knows the other coaches.
The defense clearly progressed this year. It wasn't pretty and it wasn't dominating, but it progressed significantly. And we saw large progression from players like Crawford, Carter, Durant, Church, Wilcox and even Carr and Heath.
If we didn't see any progression or not enough to say so, then I would look to find a D-Coordinator who has coached the 4-3. Since we saw progression, it's best to stick with what we are doing and continue to develop many of the players we have and bring in new players.
It's a risky thing to bring in a new D-Coordinator from outside because he may not know how to best coach certain players, he's going to be working with assistants that probably were not his first choice and he may not understand how you play certain teams in the division (that's why divisional rivals play each other tough, they know how to play each other after a while).
I also think it would send the wrong message to the other coaches. Eberflus has been raved as one of the bright young defensive assistants in the league. He's been with the team since 2011. He could have complained his way to New Orleans when Ryan was fired and followed him there, but he didn't. In the meantime, we had a great season from our LB's. If each LB came back next season and stayed healthy, I dare say we have the best LB corp in the league.
So to do all of that and not promote from within sends a bad message to the other assistants.
YR