Did you read my post? I specifically said that I agree that winning % is not the only thing to look at when judging a QB. I merely said the way the OP tried to argue the point actually worked against him.
I don't think it does. The tweet that was posted showed that Tim Tebow has a better winning percentage than Phillip Rivers. Hopefully, no one here would argue that Tebow is a better quarterback than Rivers, or even close.
So if Tebow has a better winning percentage and is a worse QB, then wouldn't it stand to reason that no matter what Prescott's winning percentage is, he could be a worse QB than others? The point defeats any post that uses winning percentage as an argument for the quality of the quarterback.
I believe the point of the OP is that winning percentage doesn't equate to good quarterbacking, so I can't see how the point works against the OP by pointing out Dak's winning percentage.
Maybe I'm missing something here in what you are saying. My belief stands, though: Winning percentage should not be used to judge quarterbacks. You say it's "not the only thing to look at." I say, don't use it at all because the quality of the team as a whole is going to determine winning percentage, not just the quarterback.
Would Dak have gone 13-3 if he had been drafted by the San Francisco 49ers? Absolutely not. Would the 49ers have finished better than 2-14 that year? Maybe. Does that mean that Prescott didn't play a part in Dallas going 13-3? Absolutely not, and he deserves credit for playing well.