by Adam Tarr
One stat that remains frustratingly difficult to find is Yards After the Catch, or YAC. Unless you're reading a gamebook from a Buffalo Bills home game, it's rare that you will find any recorded information about a game that details how much distance each pass travelled through the air, and how much distance was covered by the receiver after the catch. This information is significant, because as Brian has mentioned in the past, the evidence suggests that receivers deserve the lion's share of the credit for YAC.
Season-by-season YAC numbers for receivers can be found for all active receivers on a few sites, but YAC numbers organized by quarterback are even harder to find. The best I've found is stats.com, which lists the top 20 QBs by YAC in each conference for each season from 2006 to 2010.
That's pretty slim pickings, but I decided to make the best of it and see what I could mine out. I took every rate stat-qualified QB this year, plus any other QBs that had 1000+ attempts in the 2006-2010 span, and attempted to merge in the YAC data with the rest of their stats. The regular stats won't line up perfectly in this case, because I didn't include any numbers for any QB from a year where they didn't finish in the top 20 in their conference in YAC (Tom Brady in 2008, for instance), but it's pretty close. Anyway, here are the raw passing totals and YAC totals for the 39 QBs that qualified for the study:
|Player||Yards, 2006-2010||YAC, 2006-2010|
Most fans could probably have guessed the top nine correctly (at least if they remembered who had a job in 2006), but it's interesting to see which QBs are more reliant on YAC than others. Some QBs get more than half their totals from YAC, while on the other extreme you have QBs like the Manning brothers who rely on the vertical passing game.
Pro-football-reference.com puts together all sorts of tweaked "yards per attempt" stats. I decided to use the data above to cook up my own, cribbing off the ideas Brian used in his old revised passer rating article.
My formula for "Normalized, Optimized, Air Yards Per Dropback" is:
NOAY/DB = (Passing Yards - Sack Yards - YAC - 32*INT)/(Attempts + Sacks) + 3.9
The 32 is in there because that preserves the ratio of INT and yardage Brian used in his passer formula. The 3.9 is in there because it gives the average 2010 QB a NOAY/DB of roughly 6.2, which is the average yards per attempt this year.
Here is the table of those same 39 players again, this time sorted by NOAY/DB, with their traditional Y/A numbers also listed for comparison:
The top of that list pretty much speaks for itself, but this list does contain some surprises for most fans, such as Favre's location near the bottom.
Hopefully someday play-by-play data will include yards in the air and yards after the catch as a matter of course, and we will be able to use this data to more precisely separate out QB and receiver contributions on individual plays. Until then, we're left making wide-angle analyses such as this one.