Sometimes teams get lucky, and they have someone in the wings that they didn't even know has that magical quality to step in and be the new "franchise QB."
Tom Brady is an example. I don't believe for a moment the Patriots didn't anticipate Drew Bledsoe returning and becoming their QB after he rehabbed his injury. What made that kind of unique is that Bredsoe wasn't all that good of a QB with the Pats, regardless of what people want to believe. His QB ratings with the Pats was under 80, and when it came to playoffs, he wasn't even close, at about 55. Belichek had a "caretaker QB" on the field, and was winning with defense more than offense. What Brady did was nearly unexpected. There was absolutely nothing that could predict the type of career he's had. His college work was decent, but nowhere near what anyone could say is spectacular. He was picked in the 6th round of the draft.
What Brady offered was someone who sat on the sidelines and learned the game, honing his skills, and developing his personal level of playing ability "within a system" that he was fit to run. I keep throwing that out in comments because you just couldn't use a Michael Vick in the Patriots system, and win games. He was a loose cannon on the field, and didn't have the patience and smarts to read what's "gonna happen" like Brady can.
It's what separates Brady and Rodgers from others in today's game. A little behind them in this skill would be Luck, Big Ben, Breez, and Rivers. You may add names, or subtract if you'd like, this is just my opinion. You could make a case for adding Ryan to this list, and possibly even Wilson, in my opinion, but they're a couple inches behind tier 2.
If the Packers pull the trigger next year, it will take two years on the bench, learning, and development, before the guy is even ready to think about getting real field time. In the third year, he would be ready to step in, if needed, and could develop the rest of the way in games. Before then? You're going to hurt a guy who isn't ready. Confidence is so darned much of the battle, and it can be shaken easily.
Next year is the perfect time to grab the next QB, if there's one out there, that could be considered the right person. It don't need to be in the first or second round, but it must be someone that has the specific attributes that allows him to be coached into being the right guy to step in, when he's needed. Way too often teams look at a guy out there and grab him, because he's good, and he ends up a square peg who can't fit into that round hole.