"The fullback is disappearing because we live in a pass-happy world now"

-- Ravens fullback Vonta Leach

You may have read the quote above in ESPN.com's look at endangered NFL positions last week.

So where have all the fullbacks gone?

In the 2008 season 14 different teams used a fullback as a regular part of their offense (part of the five most often used player positions, excluding offensive line and quarterback), but through five weeks this season, that number is down to just two, the Minnesota Vikings and the San Francisco 49ers.

So where have all the snaps that fullbacks used to get go now?

Increasingly those snaps are now going to slot receivers, but before they took over teams were opting for a second tight end to get the playing time. These changes in personnel have coincided with the increased percentage of called passing plays (pass attempts, sacks and scrambles) from 57 percent in 2008 to over 62 percent through five weeks in 2013.

The first shift started in 2009 and lasted through 2011 with the “fullback snaps” going to a second tight end. That trend peaked in 2010 when 16 teams used a two tight end offense as their base formation. This trend resulted in the number of teams using a two running back set falling to five.

A second shift has started to emerge that began in 2012, with the second tight end now being replaced by a 3rd wide receiver, usually lined up in the left slot. So far this season 14 teams are using a 3rd receiver as part of their base offense, up from 11 last season and 10 in 2011.