About the data
There are 200100 passes in this visualization (and about 300000 other plays), from the 2002-2012 seasons (only regular season games are included). This comprises every pass attempted, regardless of completion or penalty during the play. Currently, each pass has eight attributes stored with it: the quarter, the time elapsed, the down, how many yards until 1st down (or touchdown), the yardline of the play (not the line at which the pass was executed), the total yardage of the play, and whether the pass was intercepted or completed
The dataset was created by a simple python script that parses Brian Burke's dataset posted at his Advanced NFL Stats blog.
Why not SVG?
I don't think we could make a sufficiently responsive visualization of 200K datapoints using SVG. If we could, we would have certainly used d3.
It doesn't work!
Facet uses WebGL, so you'll need a fairly recent video card (anything from 2009 vintage on should be ok). You'll also need Google Chrome or Safari. There's a minor bug in Firefox which prevents it from working there. I could write code to have Facet work around it but I have other things to fix, sorry.