The most important measurement (statistically speaking) in my view when measuring the success and capabilities of the QB is the win/loss record at the end of the year. If the team wins, the QB has almost surely done well. If the team loses, the QB has likely not done well. Of course no team lives or dies by its QB play alone. But, if the QB does his job well, the receivers, RBs, etc. have a chance to be successful. The team will be relatively mistake free and have a chance to win most games. As many so often state on this board, the QB first and foremost should be a 'game manager' and get the offense executing the plays properly, timely and confidently. The QB is the leader of the offense and should be a take charge, bold and assertive commander. He can lead by example but he also needs to be the 'conductor' and directing the performance by his 10 teammates on each play. He needs to know the plays, the roles of each of the players on the field and be a 'field general', with a thorough understanding of the game plan, the playbook, the times and places and situations where each play would or would not be appropriate, etc. He needs to be coach-like in many ways. Cool, calm and mentally under control and be able to see the big picture.
A QB who can do all of the above, and also be a tremendous athletic specimen with great break away running skills (speed, power, balance, agility, strength, toughness, heart, ability to throw and catch, etc.) is extremely rare and special. All teams should covet and recruit for these traits. But focus on first getting the mental and leadership skills. The physical gifts come second, in my view.
Hopefully, POB has plenty of the former and good dose of the physical tools too! I think Tommy Armstrong has the physical skills to be a tremendous QB but has not yet shown all the consistant abilities in the 'field general' areas. If he manages to grow into the true leader we want him to be, he will long be remembered for the great team he led to the Big Ten championship. If he performs comparably with his first three seasons, no matter how many yards he has in the 'total offense' records, he won't be remembered as one of the Husker greats.