Adjusting the Dalton Scale

Andy Dalton has long been identified by NFL analysts as the dividing line between passable and non-serviceable quarterbacks in the league.  However, some stellar play from Dalton in the past year may suggest that he has surpassed his own standard as the definition of QB mediocrity (though it should be noted that NFL mediocrity is something to which many QBs aspire and have never attained).

To this end, let's break down Dalton's numbers from the most recent season and compare them to his past statistics.  Using data from Foxsports.com and a little mathematical manipulation (addition and subtraction to ensure mutually exclusive events), we arrive at the following table:

Years	Incomplete, INT	Incomplete, no INT	Complete, < 20 yds	Complete, 20-39 yds	Complete, 40+ yards
'11-'14	66	788	1127	130	44
2015	7	135	203	41	11

While the counts of events is useful for transparency and ensuring these results can be reproduced, it is not very helpful in conducting an apples-to-apples comparison of these events, which we'll accomplish by way of reducing these numbers to relative percentages before displaying them:

The associated chi-square statistic (chi-sq=12.73, df = 4, p-value = 0.013) that tests if these two distributions are statistically different was significant (p < 0.05), meaning that it unlikely that random variation is driving the observed differences here.  The most notable difference is the 4.3% improvement of completions in the 20-39 yards category that actually contributes the majority (72.5%) to the significant chi-square statistic of 12.73.  So perhaps we can conclude that Andy Dalton's improved deep ball has moved him past the status of a merely passable signal-caller.

Still, I'm skeptical that this comparison is for a full 16 games from 2011-2014 but only the  first 13 games of 2015.  As such, let's explore if this may be a confounding factor in the previous analysis.  Just to vary our methods a little, let's compare Dalton's passer rating from the first 12 games of every season, as he was actually injured early in the 13th game:

	Games Played	Avg QBR	SD of QBR	p-value of t-test
2015	12	111.6	26.8	0.007
'11-'14	48	86.2	28.2

So the observed difference of 25.4 (±18.4 for 95% Confidence interval) in Passer Rating in 2015 pushes Dalton well past the mediocre, even after adjusting for potential differences in early season performance.  So we'd still conclude that Andy Dalton played significantly better in 2015 than in 2011-2014 using Passer Rating.  While this 2015 performance may still turn out to be an anomaly, perhaps we should start looking for a new standard of merely passable quarterback in the NFL.