From the article you just linked:
Which lends more credence to the idea that if he doesn't fit, he won't help.Nearly every quarterback is a system quarterback—the few players who can succeed in multiple schemes with different personnel can be counted on one hand. Tom Brady is the only example in NFL history that comes to mind among players who have done so at a championship level
By the way, I'm not anti-Kaep. If they got him, I'd think it would mean two things: 1) they've known all along Hundley isn't NFL material and have been playing a risky game of "hold the live grenade"; 2) it will take several weeks before he gets comfortable in any system M3 devises for him. I honestly think the Packers best chance of winning is going with Hundley who they've trained for three years for a moment such as this.