http://www.fangraphs.com/fantasy/index.php/whats-wrong-with-rickie-weeks/ Well, that article is also using it incorrectly. If you look at the numbers, Weeks has a LD% of 16.7%, a GB% of 44.7, and a FB% of 38.6%. Conveniently that adds up to 100%, or all of his total plate appearances. If he hit an IFFB on 15.7% of all of his PA...that would mean 40+% of his flyballs land in the infield (15.7/38.6), which just doesn't seem right when you think about it for a second. Also, if you go to his 2003 stats on fangraphs he had an IFFB% of 66.7%, which was higher than his FB% of 50%. And that is not mathematically possible, unless FB% only counts balls to the OF. Which it doesn't, because as we've established LD%+GB%+FB%=100, which wouldn't work if infield flies were ignored. FB% counts both infield and outfield flys, therefore if IFFB% was IFFB/PA it would be impossible for it to be higher than his FB%. It has to be (and it is) IFFB/FB. Again, not questioning your initial point (Weeks is popping up a lot....although that number has dropped almost 5% in the three weeks since that article, so maybe he's making better contact/normalizing to his career rate of 13.7%), just trying to help explain the stat.