He came into a good situation, more than good, it was great.
No idea who made the Haley choice, it's usually the coach but I have no knowledge of what really went down. Most coaches live and die by their coordinators, Tomlins joining the club.
Also wonder how much front office talent they've lost over the years, happens to all good teams. They found some late round gems at WR, but they haven't hit on defensive replacements. It happens though, hard to be consistent in that department, you're going to have misses, but its tougher when it catches up to you all at once.
Edit: bad luck with injuries too, exposes depth problems immediately.
