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4th Down Review, Part 1: Mike McCoy and the San Diego Chargers

Jason Peters takes a look back at coaching decisions on fourth down. In this first part, he looks specifically at Mike McCoy, and finds out how much improving decision-making could help the San Diego Chargers win.

Kirby Lee-USA TODAY Sports

It is no secret that I have been critical of Mike McCoy's decision making on fourth down this season. I've posted week after week criticizing him for not going for it often enough. I do try to be fair, and when a decision is a toss-up, I'll often acknowledge it. I'll even praise him for the instances where he makes the correct decision.

That being said, you won't see much praise in this post. This post is about missed opportunities, and how those opportunities add up. Over the course of 18 regular season and playoff games, Mike McCoy had to decide whether to go for it, punt, or attempt a field goal on 114 fourth down plays. How well did he do making the optimal decision, and how much did sub-optimal decisions cost the team?


For every single Chargers 4th down this season, including the playoffs, I input the game situation into the Advanced NFL Stats 4th Down Calculator. The 4th Down Calculator will give a summary in 2 different measures, Expected Points and Win Percentage. For most of the game, the objective would be to maximize your points, so I (for the most part) used the Expected Points measure to determine the optimal decision.

However, like the New York Times 4th Down Bot, I switched to Win Percentage if either team is up by 14 or more points, or if there are fewer than 10 minutes left in regulation. At those times, the best course of action isn't necessarily to maximize points, but to maximize the probability of winning. This resulted in 76 plays evaluated by Expected Points and 38 by Win Percentage.

Overall Result
Total Plays Optimal Decisions Points Lost Win Prob. Lost
114 68 (60%) 18.1 0.55

The results from the stats are not terribly encouraging. Mike McCoy only makes the optimal decision on whether to go for it, punt, or kick about 60% of the time. On the plays evaluated by expected points, the end result was a loss of 18 points over the course of 18 games.

One point per game lost doesn't sound that bad, but it can be significant. Including their two playoff games, the Chargers had 10.5 Pythagorean wins based on their points scored and points given up. If 18 points are added to the point differential, the Pythagorean win total for the Bolts rises to 10.95, an addition 0.45 wins. Add that to the win probability lost over the course of the season, and Mike McCoy cost the Chargers a full win on 4th down decisions alone.

Now, the common complaint is that no one really expects a coach to go for it in his own territory, or on 4th and medium or longer. Well, let's break down how he did on those specific situations, both separately and combined.

It is fair to note that a huge chunk (nearly half) of the win probability lost came on one play, when Mike McCoy opted to kick the field goal to tie at the end of regulation against Washington, rather than go for the touchdown from the 1 and the win. That decision can be broken down here.

In Opposing Territory
Total Plays Optimal Decisions Points Lost Win Prob. Lost
62 31 (50%) 14.4 0.34

The Chargers had 62 fourth downs at midfield or further, and Mike McCoy made the best decision on exactly half of them. This poor decision-making resulted in 14.4 expected points lost, and a cumulative win probably of 0.34 wins.

While there is a slight drop-off from McCoy's overall rate here, it isn't too far off, unlike the following sections.

On 4th and Short
Total Plays Optimal Decisions Points Lost Win Prob. Lost
37 9 (24%) 15.4 0.39

Mike McCoy was called on to make the call on 4th and 3 or fewer yards 37 times over the course of the season. He made the optimal decision a mere 24% of the time, resulting in a loss of 15.4 points and 0.39 wins.

It should also be noted that two of these optimal decisions are actually fake punts that were likely called by Eric Weddle, not Mike McCoy. It is becoming clear that much of the value lost from poor decision making is occurring in situations where those decisions should be the easiest to make.

4th and short in opposing territory
Total Plays Optimal Decisions Points Lost Win Prob. Lost
22 5 (23%) 12.0 0.24

This is the money one. The situation where you should almost always go for it. Fourth and short in opposing territory, where being aggressive has great reward, and failing does the least damage. How did Mike McCoy do? Not great. Among 22 plays, he made the optimal decision only 5 times. These 17 sub-optimal plays actually account for 12 points lost, and 0.24 wins. Mike McCoy actually punted on 4th and short in opposing territory 7 times over the season.

One interesting tidbit is that one of the 5 optimal choices actually turned out to be a punt! With just under 6 minutes left in the second Denver game, the Chargers faced a 4th and 3 from the Denver 39 up 7 points. By win percentage, the metric used for this situation, the Chargers had a 91% chance of winning if punting, and 90% chance going for it. It is close, but the number actually slightly favored punting in that situation.


If Mike McCoy made only the small change of being more aggressive on 4th and short in opposing territory, the Chargers chances of improving their record in future years increases dramatically. An extra win from just improving one aspect of your decision-making is a huge deal in a 16 game season. Every advantage is needed to succeed in the NFL. This is an easy one that not enough coaches leverage.

The most common criticism in the comments of these posts is asking if Mike McCoy is really any more conservative than other coaches. The answer to that question is the subject of the second part of this series.