You didnt prove that it wasnt a good stat. You just stated it isnt a good stat because Tyrod "throws balls over peoples heads all the time." Instead of offering up a sample of QBs that have high completion percentages in NFL but can't hit the broad side of a barn, you gave pure anecdotal evidence... If I take a look at QBs from 2017 with completion percentages under 60% and over 200 attempts, I see luminaries such as Tom Savage, Jacoby Brisset, Trevor Simian, CJ Beathard. Tells me that its a decent starting point for separating wheat from chaff.