There are some major challenges assessing the quality of general manager candidates.
One of the big ones is figuring out exactly what each candidate had to do with the success of his team. To be certain there are questions with hiring first time head coach candidates. Will they be able to build a quality staff of assistants? Will they be able to delegate? Will they be able to manage a staff? Will they be too hands on? Will they be too hands off? Can they handle the media? Can they run the game from the sidelines? How will they deal with a public relations crisis?
Many similar questions exist with general manager candidates. At least with coaches, though, a body of work exists. If nothing else, we can judge their competence based on the units for which they are responsible. If the candidate is a coordinator, we can look at how successful that unit is. If the candidate is the position coach, we can see how well the team has developed players at that position. Do these things offer a complete picture and guranatee of whether somebody will be a successful head coach? Of course not, but at least there is something tangible we can use as part of the judgment.
In front offices the picture is much murkier. The only people who know the exact responsibilites of people in the front office are the people inside the facility on a daily basis. We can't say which person is most responsible for a good move.
In fact, it rarely has to do with one person. Teams tend to have many personnel people offer reports on potential acquisitions. We will never know how much one person in a front office had to do with it. Did the candidate agree with the pick made? Did he like the player? Did he even study the player? Nobody has any way of knowing.
A member of a front office might claim he loved Russell Wilson. How meaningful is that if he loved Stephen Hill more and was part of a group that got his team to trade up for Hill, depriving the team of ammo that could have been used later to trade up for Wilson?
The tendency is to transfer every move a team has made onto a general manager candidate, but that isn't necessarily a case. You might see that the Seahawks have drafted really well and think one of their Vice Presidents was part of that. It might not be the case, though. You don't know that candidate will actually turn your team into a copy of his former team.
There are also cases where a candidate is from an unsuccessful franchise like Minnesota. It's entirely possible a candidate is a good part of a bad front office team. Maybe he is giving good advice nobody is heeding. With that said, it would be a good idea to have some firm proof of this because the odds increase of finding somebody who isn't very good off a team that isn't very good. In addition, these candidates will have less experience creating a winning culture and understanding how to build a good front office.
These are issues for somebody like me trying to break down the quality of candidates, but it is an even bigger obstacle for Woody Johnson who to a large extent must rely on word of mouth that isn't always accurate.