Visualising 2012 NFL Quarterback performance with R heat maps

With only 24 hours remaining in the 2012 NFL season, this is a good time to review how the league's QBs performed during the regular season using performance data from KFFL and the heat mapping capabilities of R.

#scale data to mean=0, sd=1 and convert to matrix
QBscaled <- as.matrix(scale(QB2012))

#create heatmap and don't reorder columns
pheatmap(QBscaled, cluster_cols=F, legend=FALSE, fontsize_row=12, fontsize_col=12, border_color=NA)

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Instead of using the R's default heatmap, I've used the pheatmap function from the pheatmap library.

The analysis includes KFFL's data on Passes per Game, Passes Completed per Game, Pass Completion Rate, Pass Yards per Attempt, Pass Touchdowns per Attempt, Pass Interceptions per Attempt, Runs per Game, Run Yards per Attempt, Run Touchdowns per Attempt, 2 Point Conversions per Game, Fumbles per Game, Sacks per Game.

#cluster rows
hc.rows <- hclust(dist(QBscaled))
plot(hc.rows)

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This cluster dendrogram shows 4 broad performance clusters of QBs who started at least half the regular season (8 games) plus Colin Kaepernick (7 games). It's important to remember this analysis does not include any playoff games. Our assessment of playoff QBs is also easily biased by the results of these games – just because Joe Flacco makes SuperBowl XLVII does not mean he has consistently outperformed Tom Brady.

Cluster 1 – The top tier passers

#draw heatmap for first cluster
pheatmap(QBscaled[cutree(hc.rows,k=4)==1,], cluster_cols=F, legend=FALSE, fontsize_row=12, fontsize_col=12, border_color=NA)

20130203-221423.jpg

Pass first QBs with good passing stats and who kept out of trouble (low interceptions, sacks & fumbles). Within the group – Brees, Peyton Manning, Brady and Ryan have the best results with Carson Palmer a surprise in this group.

Cluster 2 – Successful run & pass QBs

#draw heatmap for second cluster
pheatmap(QBscaled[cutree(hc.rows,k=4)==2,], cluster_cols=F, legend=FALSE, fontsize_row=12, fontsize_col=12, border_color=NA)

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Strong outcomes in both the passing and running game including the 3 QBs who led in run attempts per game – Newton, RG III and Kaepernick. RG III & Kaepernick also had surprisingly few interceptions per game given their propensity to aggressively throw deep.

Cluster 3 – The Middle

#draw heatmap for third cluster
pheatmap(QBscaled[cutree(hc.rows,k=4)==3,], cluster_cols=F, legend=FALSE, fontsize_row=12, fontsize_col=12, border_color=NA)

20130203-221437.jpg

Not great but not the worse either including Joe Flacco.

Cluster 4 – A year of fumbles, interceptions and sacks

#draw heatmap for fourth cluster
pheatmap(QBscaled[cutree(hc.rows,k=4)==4,], cluster_cols=F, legend=FALSE, fontsize_row=12, fontsize_col=12, border_color=NA)

20130203-221445.jpg

As a NY Jets supporter this is painful.

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