A Deeper Look at the Cowboys and 49ers

NFL Wild Card – The Cowboys ended what was once a promising season in spectacular fashion on Sunday afternoon.  A late rally came up short after Dak Prescott made a daring sprint to the 49ers’ 24-yard line on the last play of the game.  With 14 seconds remaining and no timeouts, the Cowboys had hoped to give themselves a better final shot at the end zone but were unable to spike the ball before the clock expired.  Amid the chaos, the official couldn’t properly place the ball on the correct line of scrimmage as he tried to squeeze through the Cowboys’ offensive linemen.  There was a crescendo of frustration among the Dallas faithful as they felt robbed of one more crack at the end zone.  It is difficult to say how much Game-Winning Chance (GWC) was lost in not being able to stop the clock, as the Cowboys would have had one last pass attempt into the end zone from the 24-yard line. Our simulations indicate it may have been as much as 15%.  All this late-game drama obscured the fact that the 49ers made a deliberate decision on fourth down just moments earlier that was even more costly in terms of expected GWC loss than the Cowboys’ poor execution on the final play.  

With 2:51 remaining in the game, the 49ers were facing a fourth-and-1 on the Cowboys’ 49-yard line while holding on to a 23-17 lead.  They lined up as if they were going to run a play, but it was only a weak attempt to draw the Cowboys offsides.  After being assessed the five-yard penalty, the 49ers were slightly more justified with their punt on fourth-and-6. A custom simulation reveals that punting on fourth-and-1 is a massive -17% GWC blunder.  Amazingly, even after the penalty it is still a -6% GWC error to punt the ball away on fourth-and-6.  If we simplify the fourth-and-1 attempt to a one-yard gain on a success and a turnover at the line of scrimmage when it fails, the 49ers risk approximately 6% GWC to gain 19% GWC.  Therefore their required conversion rate is only 6 / (6 + 19), or 24%.  We can debate what the actual conversion rate may be (NFL average is approximately 70%), but it should be clear that within any reasonable range of assumptions, this decision is a no-brainer.

A full table of suboptimal decisions from this game is represented below. There were several other “high-confidence” errors by both teams, although none quite as egregious as the aforementioned.  The high confidence label addresses an issue raised by many readers this season.  While the underlying DVOA assumptions that inform our custom simulations are very good, we recognize there is some level of uncertainty.  For this reason, a decision is re-run with very strong counter-case parameters.  Regarding the 49ers’ fourth-and-1, even if we set the offense well below the worst rushing team in the NFL and set the defense well above the top rushing defense, we cannot come close to flipping the model’s recommendation to attempt the first down.  For example, swapping the 49ers’ rushing offense with the Giants (worst rated offensive rush DVOA) and swapping the Cowboys rushing defense with the 49ers (top rated defensive rush DVOA), the error only drops from -17% GWC to -11% GWC. 

The Dallas Cowboys coaching staff will undoubtedly endure some criticism this week as the San Francisco 49ers prepare for their matchup with the Packers.  While it is always difficult to argue with a win, our analysis reveals the 49ers coaching staff should be subjected to at least as much scrutiny as the Cowboys.

49ers key fourth down errors:
 

Cowboys key fourth down errors: