TT's aversion to adding players from other teams (whether through unrestricted free agency, street free agency, or trades) is just odd, because no other NFL GM constructs his roster that way. No one.
The point is not whether Tyler Polumbus is a better option than Don Barclay as a backup T or whether Mason Foster would be an improvement over Jake Ryan THIS SEASON, but rather that TT virtually never sees a player on another NFL team as a viable alternative to what he's got on his roster (including practice squad).
That is just weird and leads to seasons where the likes of M.D. Jennings/Jerron McMillian (in 2013) are allowed to play meaningful minutes just because they were homegrown.
TT has done many things well as the Packers' GM. He has a significant blindspot that has hamstrung the Packers, however, and McGinn rightly points that out.