There should be no question at this point that Dak is not a great quarterback.
However, using Colin's criteria ..
Aikman had trouble winning without Emmitt or Michael on the field, so I guess he was an average quarterback.
Romo had trouble winning without a great running back or receiver, so I guess he was an average quarterback.
While I like Colin and I do agree with several of the things he said about Dak, the bottom line is that the correlation between success and failure for Dak has little to do with a "great" running back and receiver being around him.
What Dak needs to win is very simple. He needs great offensive line play because his biggest weakness is pocket awareness. He also needs receivers capable of stretching the field (and catching passes) to keep defenses from stacking the box. It would also help him greatly if we had an offensive coordinator that was more creative and capable of designing plays and schemes that better fit Dak and this team's strengths.
Most importantly though, Dak needs to avoid turnovers. If Dak doesn't turn that ball over yesterday, the Cowboys would have won by at least 7-10 points without overtime.
As I said, Dak is not a great quarterback, but the Cowboys can win with him.
That said, I would still be looking for another possible future franchise quarterback