October 4, 2012 - by Gregory Matthews
QB Performance Plots For NFL Week 1: RGIII’s Monster Debut In Color
posted in NFL
This is a guest post by Greg Matthews, founder of Stats In The Wild, a blog focused on sports analytics and data visualization. If you’re interested in guest posting on TeamRankings, email us your post and we’ll consider it.
Quarterbacks come in many different varieties. Some quarterbacks are strictly pocket passers. Others are a threat to take off and gain yards with their feet. Yet it seems in an attempt to compare quarterbacks, the commonly used measure is passer rating.
One of the problems with passer rating is that it attempts to summarize the many aspects of a quarterback’s performance with only one number.
An alternate approach is to visualize the differences quarterbacks using a plot that displays each individual characteristic of a quarterback to create a shape. Then one can compare the shape of each quarterback to the shape of another quarterback to see the similarities and the differences.
As an example, here is a plot of all quarterbacks from Week 1 (click to enlarge):
At the top of the plot, you’ll see the key, which tells us that the segments each represent rushing yards (RYDS), TD to interception ratio (TDIR), completion percentage, passing yards per attempt (YA), and total passing yards (YDS).
I’ve scaled the data in such a way that a fully filled-in semi-circle (like the one at the very top) would represent a quarterback’s performance if he had:
- Over 50 rushing yards
- TD to interception ratio of at least a 3:1
- 80% completion percentage
- Greater than 12 yards per pass attempt
- Over 450 total passing yards
(Two notes about TD to interception ratio. If interceptions is 0, I set TDIR to be 3; if interceptions and TD is 0, I set TDIR to be 1.)
On the other hand, a completely blank space would indicate a quarterback with:
- 0 yards rushing
- TD to interception ratio of 0
- Less than 50% completion percentage
- Less than five yards per pass attempt
- Fewer than 150 total passing yards
Basically, bigger is better here. Just compare Robert Griffin III, who had a tremendous game in week 1, to John Skelton or Brandon Weeden, whose Week 1 performances were…um…less than tremendous, shall we say.
This also allows us to easily compare quarterback performances in a visual manner. Take Mark Sanchez and Joe Flacco from week 1. The shapes representing their games are nearly identical. This is clearly reflected in their stat lines:
- Flacco: 21/29 (72.4%), 299 YDS, 10.3 Y/A, -1 RYDS, 2 TD, 0 INT
- Sanchez: 19/27 (70.4%), 266 YDS, 9.9Y/A, 0 RYDS, 3 TD, 1 INT
But it’s much easier to compare their shapes to one another, than try to compare all the numbers in those two stat lines in text or tables.
One other aspect of quarterback performance that these visualizations clearly illustrate is the difference between mobile quarterbacks and non-mobile quarterbacks. The graphics for quarterbacks like Vick and RGIII convey their penchant to rush for first downs, whereas the graphics for quarterbacks like Brady and Sanchez reflect the characteristics of a pocket passer.
What do you think of these visuals? Do they help you better understand the differences between QB styles, and quickly identify which QB’s had big weeks? We’ll publish graphics for the following weeks of this season over the next few days.