Like most things, the Fulgham situation requires nuance and an admission that we just don't know certain things.
He's been a good player for the Eagles at a position that the Packers could use the help. So the fact that they cut him was a mistake, at least in terms of outcome. We don't know what Gute/Petals knew or didn't know when they made that call. I kind of doubt that Fulgham was tearing it up and they said "no thanks." But I can also see how you would hold that against the GM at least a little bit if he's also getting credit for finds like Lazard.
On the other side, given the circumstances of his time here, I see nothing homerish about fans shrugging it off. The reality is that lots and lots of undrafted guys typically bounce around until they succeed somewhere. And oftentimes it's not because of mis-evaluation, it's because the player himself clicks and makes a leap. The Rams' great defense is starting a corner right now, Darious Williams, who got cut in Baltimore and is now playing like a pro bowler. The Ravens have one of the best personnel departments in football. It happens.