[Goose]

So that year, we had easy games and hard games too.

BC

For sure each year we have easy games and hard games. I am not saying the average yards per carry lies. I am saying it delivers exactly what the average of a small number (12 or so) of differently distributed,  time varying, and probably not very random measurements promises to deliver. The YPA delivers not very much. This is probably a good thing. If it were a good, strong statistic, we could use it to predict the scores of games with very high accuracy. Fortunately, we can't, and therefore we can talk about it  ;D.  We use these statistics not because they are particularly strong, but because they are all we have. They are not meaningless, but exactly what they mean is very open to debate. 

[Goose]

So that year, we had easy games and hard games too.

BC

For sure each year we have easy games and hard games. I am not saying the average yards per carry lies. I am saying it delivers exactly what the average of a small number (12 or so) of differently distributed,  time varying, and probably not very random measurements promises to deliver. The YPA delivers not very much. This is probably a good thing. If it were a good, strong statistic, we could use it to predict the scores of games with very high accuracy. Fortunately, we can't, and therefore we can talk about it  ;D.  We use these statistics not because they are particularly strong, but because they are all we have. They are not meaningless, but exactly what they mean is very open to debate.