Why the Chargers will Shock the World
Is anyone picking San Diego to win Super Bowl XLVIII this year besides myself and a bunch of San Diegans? Vegas Insider has the Chargers as the biggest long shot in the playoffs at 50 to 1. The ESPN NFL Live crew all picked the Bengals to win their wildcard matchup – they don’t think the Chargers will get past the first round.
Its hard to argue with those assessments. After all, the Chargers lost games this year to Houston (2-14) and Washington (3-13). They barely got into the playoffs with a 9-7 record. They needed a controversial non-call to help send their final game into overtime, where they beat a Kansas City team that had no real incentive to win.
So why would anyone realistically pick the Bolts? To be honest, this post started out as a bit of a lark – I’ll explain why later… I didn’t do dissertation-level analysis, just enough to convince myself that the Chargers have a realistic shot at the title. At the very least, it appears that the Vegas odds are more than a little off.
Statistics are often characterized as a way to use numbers to strengthen otherwise weak arguments. “Lies, damn lies, and statistics” is a quote we’re all too familiar with. But let’s take a look at some numbers with regards to the teams in this year’s playoffs.
The Fundamental Stat – Head to Head Records
The first thing that grabs your attention about the Charger’s record is the number of quality wins over teams that are also in the playoffs. They’ve played more games against playoff teams (7) than any other team in the playoffs, compiling a 5-2 record in those games. They have wins over Denver (in Denver) and won both their games against KC (including that last controversial one).
The only team with a better record against playoff teams happens to be the Bengals, at 4-0. In fact, the Bengals are the only AFC team in the playoffs that the Chargers have not already beaten. If all you knew about the season was these head-to-head results, how would you handicap the Chargers? Definitely not 50 to 1…
The Esoteric Stat – Passing Efficiency
NFL game predictions are extremely difficult for a number of reasons. First, there’s the limited sample size due to the relatively short football season. Second, injuries at key positions can have a huge impact from game to game. Third, there’s a high degree of multicollinearity between variables for predictive models dealing with NFL games (leading to overfitting, leading to complicated techniques to deal with multicollinearity, etc.).
As a result, predictive models for NFL games tend to have a tremendous amount of variance, random errors that are unaccounted for by the variables we bring into the model. This variance may be attributed to a number of factors – such as:
- luck, chance, fate, karma, etc.
- players in contract year differential (which actually may be a valid predictor)
- the will of the gridiron gods (see 1.)
- Bill Belichick (see this)
- the ball is shaped kinda funny and you never know which way its going to bounce (see 1.)
I was a member of a project team at Northwestern that modeled NFL games using some pretty sophisticated algorithms (Naive Bayes, Random Forests, Neural Networks, Support Vector Machines etc. along with Monte Carlo simulations and extensive validation testing). We arrived at a couple of conclusions:
- the optimal model changes year to year. We can speculate as to why, but that’s a different tangent…
- passing efficiency is the most reliable predictor of wins for every year we studied.
Interestingly, passing efficiency turns out to be a better predictor than the passing efficiency ratio (which factors in the teams’ defensive passing efficiency) for the years we studied. Interpretation of this finding is also a different, albeit interesting, tangent.
There are several estimates for passing efficiency including Net Yards per Pass Attempt and Football Outsider’s Passing DVOA. Here’s how the playoff teams stack up in terms of our passing efficiency proxies (these are based on the 2013 regular season):
Clearly, Denver and San Diego have separated themselves from the rest of the pack in terms of passing efficiency (btw, its good to see that the two stats appear to have a nice positive correlation). In fact, the Chargers’ Passing DVOA (I love this stat from Football Outsiders) of 51.3 crushes the Bengals’ 13.7. Based on our passing efficiency metric I’d say the Wild Card round goes to the Chargers.
But, assuming they get past the Bengals, their next opponent would be the Broncos, who have a higher passing efficiency rating. What gives? The Chargers are 1-1 against the Broncos this year, with their win coming in Denver. So, they’ve shown that they’re capable of winning in Denver, but the real reason I’m picking them is…
Two Really Obscure Stats – LTTR and PIP
As I mentioned, the Chargers lost to Washington earlier this year. This fact brings to mind the emerging ‘LTTR’ phenomenon. In recent years, if you lose to the Redskins, you end up Super Bowl Champs. Let’s take a look at recent Super Bowl winners:
- 2013 Ravens. Lost to Redskins 31-28 in OT
- 2012 Giants. Lost to the Redskins twice
- 2011 Packers. Lost to Redskins 16-13 in OT
- 2010 Saints. Should have lost to the Redskins but won in OT in miraculous fashion.
As a Redskins fan myself, I’m keenly aware of the recent LTTR effect – which was the impetus for my taking a quick look at who the possible beneficiaries might be this year. The Redskins only won 3 games this year, with only one of those wins coming against a playoff team.
That team is the San Diego Chargers.
Not convinced? Okay, how about the new ‘PIP’ predictor… the last 4 Super Bowl winners all played in Philly for the Eagles home opener:
- Sept 16, 2012 Eagles 24, Ravens 23. Ravens win Super Bowl XLVII
- Sept 25, 2011: Giants 29, Eagles 16. Giants win Super Bowl XLVI
- Sept 12, 2010: Packers 27, Eagles 20. Packers win Super Bowl XLV
- Sept 20, 2009: Saints 48, Eagles 22. Saints win Super Bowl XLIV
I probably don’t need to tell you who the Eagles played in their home opener this year, but I will – once again it’s the San Diego Chargers [shout out to Eagles fans Samir Doshi and Rohan D’Souza for this nugget].
“Lies, damn lies and statistics”… I guess we’ll find out in a few weeks!