There are many aspects to being a manager.
Tactical (which itself needs to broken down into segments)
Training (coaching)
Man management
Getting players to buy into what your trying to do
Understanding the little things and making sure they have the right environment
The little bit of magic
Tactically Southgate is pretty poor. At least he's beyond slow to react
Everything else he does seems okay to good though.
Sometimes fans think that all that matters is being good tactically, but that's not true. Even on the amateur game, I see young men that think they'd be a good manager, have played football manager and won the premier league so they must be good.... And yet they can't talk to people. They may have had really good coaches on the last, know all the drills, but they're terrified.
Southgate is not the best tactically, but he's a decent manager in many other ways. If he can delegate that part of his job out, he could do well.
Going places