YAC - Yards After Catch
Definition of YAC
"YAC" stands for "Yards After Catch", which refers to the average number of yards a receiver picks up after catching a pass. This stat is used by fantasy football managers to categorize receivers. In other words -- receivers can be "big YAC" guys or "touchdown" guys, etc. Depending on what hole you're looking to fill in your receiving corps, you may need a big YAC receiver, though generally fantasy football managers look down on players who put up big YAC numbers.
Most of us look for receivers who take up residence in the endzone. Braylon Edwards, Randy Moss, T.J. Houshmanzadeh -- these are all receivers who end up catching the ball underneath the goalpost. Some receivers ended up going pretty high in my drafts (guys like Wes Welker and Roddy White) who simply don't score many points for their team (or for their fantasy managers). There's nothing wrong with drafting guys with big Yards Afer Catch, but don't draft them above receivers who will regularly score touchdowns.
YAC is a tricky stat because it depends on so many other factors. Unlike YPC for running backs, a receiver's YAC requires that the QB get the ball to him, secondly that he catch the ball (not as easy as a running back grabbing a hand off), the style of the team's offense, and the way that receiver matches up against the defense.
I like the YAC statistic in fantasy football -- it helps me pick my backup receivers, and assistance with selecting backups is usually a problem in the world of fantasy sports. By picking up a couple of receivers with high YAC stats to backup your big touchdown receiver, you'll have great players who can earn you a consistent number of points each week. Don't forget that sometimes these guys have a game where they produce a ton of points for you. Just don't expect these high YAC players to score touchdowns and give you that little bonus to put you over the top.
How can you use YAC to set up your team? Some players choose to look at YAC as a QB statistic -- in a sense, a receiver's YAC is a measure of his ability both to catch a ball and to keep moving with it after the catch. However -- a team that has a few receivers with healthy YAC stats must also have a QB who can get the ball into that player's hands.
Sure, there are lots of ways to look at YAC. The key to drafting receivers is not in finding the best touchdown scorers or the guys with the studliest YAC but some balance of the two.