You have Schaub here and you worry about Barkley's feet?
With a pretty good offensive line in 2010, Barkley suffered only 8 sacks.
This past year, with the departure of a couple Senior, the injury to Holmes, the rotation at LT as I had mentioned, and having 3 different guys at LG, Barkley was pressured much more, especially up the A gaps (probably the most of among all the QBs in this class, or at least among the top) and he was sacked only 14 times in 11 games. For a QB in a pro system that is asked to go downfield quite often, that's really good.
No, he doesn't have the best mobility in the world, but he's much better than Schaub in this regard (and he's better in other regards, too).
I don't know whether you were trying to knit pick or what.
Barkley may not be a franchise QB, but he's quite likely to become a better pro QB than Schaub.
The QB has got to be able to reset his feet when going through his progression, and his completion rate shows that he's more accurate than you indicate (and that's with receivers dropping more balls for him than other Receivers did for their QBs).
And we're not talking about a guy like whathisname from Boise St the year before who seldom throw a deep pass.
What's the anatomy of a deep ball?
On a 3-step drop in the shotgun or a 7-step drop from under center, the QB has got to have good footwork to make it work well.
To get the ball downfield some 50-52 yards from the LOS (and 60 yards plus in the air) in some 6 seconds such that the receiver can catch it in stride requires a pretty strong arm. (There are other factors that can compensate: a premium angle, a quick release, good throwing mechanics that involve the legs and the arms - but still, they are all tied up together; and your assertions are scientifically impossible.)
No, Barkley doesn't have the arm strength of Jamarcus Russell or Mike Glennon; but he has plenty to do the job.