In my opinion, the biggest immediate hurdle he's face is how he handles his new authority. Management success/failure is largely determined how well you're able to delegate, and it seems that with AG's ability to coach and teach the back 7 coupled with Joe's knowledge of the trenches, there's a really good foundation to build on.
Will AG be the type of DC who wants to get his hands into everything, or will he focus on his strengths and allow the other coaches to handle their areas? Will our other coaches respect the new kid on the block, or will there be alienation issues?
As far as reasonable goals for the next year or two, the 2014 defensive stats say it all.
We ranked 114th in scoring defense at 38.6 ppgWe ranked 124th (dead last) is turnovers gainedWe ranked 122nd in pass efficiency defenseWe ranked 96th in red zone defenseWe ranked 123rd in punt return defenseWe ranked 88th in kickoff return defense
I realize the kickoff and punt defense numbers aren't in AG's jurisdiction, but I've always felt that good defensive teaching and good special teams coverage usually (not always, though) go hand in hand.
For 2015, the two most important areas of improvement need to be
1) reducing the number of big plays we allow; particularly early in games, and
2) Create more turnovers
It's one thing for a defense to get worn out as a game wears on due to depth issues, but we surrendered an alarming number of big plays early in games because of blown assignments and broken coverage's. There's nothing more devastating to team and fan psyche than falling behind at home on 80 yard bombs on the first play from scrimmage, surrendering punt return TD's, and watching the entire back-7 blow zone read assignments.
Just getting back to baseline where we make teams earn their yards/points, and create some turnovers would be a huge step in the right direction.