I'll admit up front that i've never looked into it at all, but i question how a sport that relies so heavily on teammates all performing well during each given play for it to be successful, that a sabermetrics system could evolve anywhere near like it does in a largely individual sport like baseball is. I could see studying things like down/distance and what plays then generally work best at getting first downs. I also can see teams developing numbers to rate players that fans don't know about, but don't ever see a day that football fans are discussing sabermetric numbers for say nose tackles or guards on the offensive line. Even skill position players like running backs or wide receivers that put up actual stats are so reliant of the play of their QB, offensive line, and even the play calling of their coaches. A good pass rush can make corners look good and no rush can make them look worse than they are. There are so many things that happen in football that are out of the hands of individual players that can drastically skew their stats. Randy Moss was a perfect example of this. He played in a terrible situation in Oakland, his stats took such a nosedive that many thought Randy was in serious decline. One year later in a much better situation, he shatters records during an amazing year. A good pass rusher could have a great season with 15 sacks. The next season he loses the other good pass rusher next to him, thus faces constant double teams, and his sack totals get sliced in half. You could go on and on for individual players, the situation around them that helps make them look better or worse than they really are. Baseball players face none of that, except to a slight degree pitchers and how good/bad their defense is behind them.