When you watch PJ's high school tapes, you will see a very accurate passer, who goes through his progressions, who can throw deep, and was a home run threat as a runner. It's a much higher level now, but he checks all the boxes. By now, he should have a good knowledge of the offense and his other skills remain intact.
What separates PJ so drastically from Book is his ability to throw the deep ball accurately. This is exactly how Clemson beat us: three long TD passes from an elite, freshman QB, two of which were caught by an elite freshman WR. Clemson does not hesitate to use freshmen if they are the best players. Kelly does. He's afraid. He wants to play it safe, be reactive rather than proactive. During the preparations for the Clemson game, Kelly said that he was looking to get more speed in the game at WR. Wow! Would Lenzy and the other freshmen burners get their chance? Of course not, Kelly chickened out.
Guts, meritocracy, and PJ are needed.