When I have the time I might revise the rankings after I take out all special teams and defensive scoring. It would be interesting to see the results. However, they would not be favorable to McCarthy as a playcaller.
One indicator of trouble might be the huge difference in the offensive rankings between scoring and yardage. The Cowboys are #2 in scoring, #15 in yardage.
This is typically an indication of very favorable field position due to defensive turnovers or elite special teams or both. The points ranking is more of an indication of where the entire team is whereas the yardage rankings are related almost exclusively to the offensive production.
The Chargers are currently ranked #7 in offensive yardage. They average 5.6 yards a play and the Cowboys average 5.2 yards a play.
However, the Cowboys turn the ball over far less, ranking 5th while the Chargers rank 12th.
Penalty-wise, the Cowboys have 9 more penalties but they are exactly even in penalty yards at 378.
One offense might be doing slightly better overall but it is not a commanding lead. Besides, it's not the productivity of the offense that matters, it's where that productivity takes them. Ultimately, the HC is the one held accountable.