I don't think he is particularly good at identifying "margins-players". Just look at the guys he signed last year and the unnecessary dead money they created on the payroll. In general though, I think Jed is a really smart guy and would be a very good GM in a vacuum, but unfortunately for him the other MLB teams don't operate in a vacuum. In video game terms, he might dominate the single player mode, but he camps in a corner in multiplayer, afraid to make the wrong move and expose himself to enemy fire.