IMO whoever the Packers might pick up as a backup the week before the season starts is going to be limited.
I'm with those who think Young could have been a better option than Wallace. But Wallace does have one thing that Young doesn't, namely more experience in picking up new systems. Arguably a "career backup" is a better choice for a short term replacement than a starter trying to re-invent himself as a backup.
Personally, I'd rather have someone who can play sandlot, given the current offensive line. If Rodgers goes down, it's 99% likely it happens because the OL hadn't been performing well enough in pass protection. I'd rather have a sandlot player who can make things happen with his legs than expect a backup without any training camp/preseason action in this system to "master more of the offense".
As has been repeatedly said, and I agree, this team has no serious playoff possibilities right now if Rodgers goes down long term. What you're looking for -- or, IMO what you ought to be looking for -- now is someone who can get the job done for 2-3 games.
For 2-3 games, given a choice between "career backup" and "sandlot quarterback", I'd take my chances on the latter.
But that's me.
And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God.
Romans 12:2 (NKJV)