Agreed about the line not being outstanding, but four out of five are quality players. As a unit they may not be producing as they should especially in the running game, but they have the ability to play better. I would be more concerned if they were at their talent ceiling, but am still somewhat concerned that they aren't playing up to that level yet.
I would call Barclay a proven veteran no matter whether he was drafted or not. There is no long list of teams in the NFL with starter-quality backups on the O-line. The only gamble was at center. Let's also remember that this team has invested two #1 picks in the OL over the past five drafts. There have been stronger needs in other areas recently but frankly who cares. Most of the Packers best lineman have come from the 4th and 5th rounds: Sitton 2008-R4, Lang 2009-R4, Bakhtiari 2013-R4, Linsley 2014-R5, and we soon might be able to toss Trettor in there 2013-R4.
If anything, we should toss another 4th or 5th round pick at the OL and then concentrate on other areas of need.