We've all heard it. Peyton is arguably the greatest fair weather quarterback in the history of the NFL.
I know that it crossed my mind, and many of your minds during the Baltimore loss in last season's playoffs. That said, Manning still posted a QBR of almost 90, and threw for just shy of 300 yards. Even the most cynical of us would have a tough time pinning that loss on Manning, despite the bitter cold. This got me thinking. Is the idea of Manning's performance levels being directly related to weather conditions a fallacy? We hear this statement thrown around a lot, but I cannot recall ever seeing a real statistical breakdown...
Introduction and Disclaimers
Before you read any further, there are a couple of things that you should keep in mind.
Firstly, this is hardly a definitive statistical analysis. I'm not a huge stat guy, I did this for my own interests but thought that some MHR readers might also find interest in the piece. If I've made any errors in my tests, please do flag these up, but try not to tear me apart!
Secondly; I'm going to try and keep this as neutral and purely factual as possible. Statistics are a great measure of performance, but it is important to take into account that football is a human endeavor. There are millions of variables to take into account (Peyton cannot control the other 10 players for example), and no matter how statistically significant something may appear to be, it does not make it definitely so. This isn't biology and chemistry class. I have only attempted to bring a quick focus to a few key statistics. Hopefully though we'll at least be able to spot some trends.
For anybody with ANY sort of interest in statistics, if you haven't already then do check out pro-football-reference.com. All of the data I used for this analysis was taken from that site. I took game logs for every single Peyton Manning regular season game prior to his arrival in Denver. I then also took the temperature readings for each of these individual games. I did not include playoff statistics (as it could be argued - and has in the past - that Manning is simply not often at his best in playoff situations, regardless of the colder weather in January), nor did I include last seasons statistics as any 'struggles' (a word I use lightly) may be attributed to his rehabilitation.
It is worth noting that any indoor game is registered at 72 degrees (f) - i.e. relatively warm conditions, with 0 wind. Given that around half of Peyton Manning's games were played in these conditions, I realize that any correlations could arguably be skewed by home-field advantage arguments, or the idea that Manning just plays better indoors (though it might be fair to assume that this in itself would be as a result of the calm conditions).
If anybody would like this data sending to them, I'd be more than happy to share it with you! Now onto the analysis.
The above graphs depict Peyton Manning's Average Quarterback Rating against the temperature (f) in a game. There does appear to be a positive correlation, albeit quite weak. The spikes and troughs are mostly a result of only one or two games having been played at an exact temperature, but what is clear that Manning's worst games have come in the coldest conditions - even if the overall correlation is only very weak.
Using a quick Spearman's Rank test, it was determined that there was a correlation co-efficient of 0.31. This is relatively weak, though assuming my calculations are correct (largely a result of Manning's healthy sample size) with a T-test score of 2.15 we can assume that there is a less than 5% probability that this correlation occurred by chance.
The quarterback rating system has its critics. Winning is much harder to argue against. Again I used Spearman's Rank methodology to test for correlation in this case. Interestingly my results were significantly stronger this time around. I calculated a correlation of 0.4, with a T-test score of 2.5. In essence this means that the correlation was stronger, and there was less room for error.
By making a rather hideous looking graph, a line of best fit clearly shows this correlation between better conditions and win percentage:
The aim of this project wasn't really to reach a conclusion, it was rather a way for myself to just ever so quickly and briefly explore the notion that Manning was genuinely a better player in warmer conditions. Again, this is hardly definitive (I only actually mapped a total of 3 simple variables!), but thought that I might share it with you guys at MHR. It's probably fair to assume that almost all quarterbacks play better in more favorable weather conditions. That said, there certainly does seem to at least be a correlation in Manning's case, particularly when it comes to winning football games.