Here's all of the information I really need on Zappe, without even watching him in the games, which only furthers the point.
The Pats waived him, and 31 NFL GM's, all of whom probably know more about football than anyone on this site, didn't bother to even bring him in for a workout, never mind sign him for pennies as a 2nd or even 3rd string backup. That is a glaring bit of evidence that he's just not that good. Now, I suppose every GM in the NFL missed on him, and he could go out and light the world on fire someday, but I've done the analysis about backups and rookies coming into the league for stretches of good play that last 3-4 games, and then their true talent level shows up. I've seen nothing from Zappe that suggests he'll buck that trend.
That said, to be fair to him, nobody would buck that trend with this current roster.