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San Diego Chargers head coach Mike McCoy's margins of victory

Just how close (or not) have Chargers games REALLY been under Mike McCoy?

Charger head coach Mike McCoy, anxious for the results of this article
Charger head coach Mike McCoy, anxious for the results of this article
Chris Humphreys-USA TODAY Sports

I recently reacquainted myself with a metric that I thought would be interesting to apply to the tenure of Mike McCoy Charger teams, especially since the database over at Football Perspective (top right corner) also goes back to 2013. Football Perspective calls it "Game Script", but what it essentially represents is the average margin of victory. Traditional margins of victory only describe the game at the point the clock has expired. A margin of 21 points could be indicative of an early large lead or of a surge in the final minutes of an otherwise close game. A game script would multiple the point margin at any given time in the game by the number of seconds there was that margin. We add these together & divide by 3600 seconds (or more, if the game reaches OT), to find what the average point margin was at any point during the game. This paints a clearer picture of one team’s dominance or lack thereof and allows us to examine a few different trends. (Just trends, I swear! I’ll leave the raw, dry data (including each individual game) to the table on FP).

(Preface: Obviously these numbers do not have a flat-out objective tie to McCoy’s coaching abilities, we just tend to assign measurements of success (especially of a well QB’d team) to the head coach; and since we fans have been increasingly critical of him, I thought it was worth a look).

First, let’s look at what percent of games where the team was, on average, leading but ended up losing the game

leads lost

In each of these years, the Chargers had a positive average margin in roughly half of their games (2013 to 2015: 9, 8 & 7 games respectively). What this says in-&-of itself, I’m not sure. What we can see in this graph though is that the team continued to lose a higher % of games where they had generally been in the lead. From the first to second year there is only a slight increase (2 leads-lost each, just with a lower total of leads in 2014), but in 2015 the Chargers lost a whopping 57.1% of the games they had been primarily leading. We’ll touch on this trend later, with a possible explanation that may or may not shock you….okay, it’ll shock no one.

(Note: The median margin (the middle value, not changed by extreme outliers, as average is) of 2014’s leads were the highest of the group, 5.2. 2013’s & 2015’s were roughly the same, 3.8 & 3.9 respectively).

Next, let’s acknowledge the positive and see what percent of games where the Chargers primarily-trailed were won!

trailing won

While the differences are not as extreme as the losing graph, in 2015 the team once again failed to come from behind, relative to the previous years – only 1 victory was had in 9 primarily-trailing games. Impressively 2014 had both the highest win% (37.5) and the largest trailing median margin (-6.6).

This next graph shows the win% of games where the margin was within +7 to -7 (note: because these are the average margins of victory, I’m not sure how relevant this is to idea of literally being actually up or down a TD at any given point, it was just the simplest number to settle on).

close win%

The sample size for each year was roughly the same – the majority of games (11 in 2013 & 2015, 10 in 2014). Like the leads-lost graph, the numbers in 2013 & 2014 are very similar, but those in 2015 are considerably worse (27.3 W%, compared to the low 60’s). Close games were not a strength of the 2015 Chargers.

Additionally, of the 24 road games the team had under McCoy, 62.5% of them (15 games) had a negative average margin. Only 4 of these games were eventually won – just 26.7%. I do not know the league-average numbers for this, but I would venture to say that road games are a weakness of this team. (And perhaps, it could be argued that this could be more strongly related to coaching/team management). Also, the average game script has been decreasing each year of McCoy’s tenure: from 1.32 to -0.53 to -2.52. (Note: average meaning I averaged each set of 16 numbers, not the full out per-second averaging that goes into each game’s number – so these can be affected by outliers. In the next section, you can see the median numbers were still in decline).

Finally, let’s examine what I believe shines some statistical light on to why the team couldn’t hold on to leads in 2015. This chart shows the game scripts of each season (trailing to leading), along with the percent of plays where the team passed the ball.

GS pass%

Looking at the color-coding, you can see in 2013 & 2014 that in general the team followed along the path most teams do – passing more when you’re trailing, and running more when you’re leading. In 2015, however, there are noticeably more high-pass% performances near that leading end of the table. We don’t have to connect a lot of dots to figure that many of these leads were lost because there was not a reliable running game to rob the opponent of comeback-time. Granted, it is possible to gain chunk/possession yardage with a well-orchestrated passing game – and perhaps that could have been done….if only superstar chain-mover Keenan Allen hadn’t been sidelined half the year by a freak kidney injury. That said, I would argue that the rushing attack is the primary culprit and that it must be "fixed" (however you think we should do that) if we can expect any stability in holding on to leads, (reacquiring the offensive coordinator of the most successful & stable team in this tenure can’t hurt either).